Ok, so at this point I would normally load up Stellaris so that I can cross-reference the game's data with CoaDE and with the Life2.0 thread; we are after all at the point where we are seeing Stellaris technologies being implemented.
But... The laptop can't cope with Stellaris anymore.
Unfortunately...
12m diameter pusher plate ships are essentially too small to fit into Stellaris' ship classification scheme. Which I'm not sure what to think of, given the Orion battleship Kennedy saw a model of and cancelled the project used the 26m pusher plate we'll look at now:
26m pusher plates are Corvettes:
This one represents a Planetary Defence Corvette. 26m pusher plate, small shuttle pod bay, 2x 50MW lasers for point defence and sub-system targeting, and 1600x 1kt nuclear warheads, of which hopefully at least one will get through enemy defences at detonate at point blank range and flood the enemy vessel with x-rays and neutrons. (an easy upgrade if you don't mind taking longer to get to orbit is bolting on more missiles, as switching to 16 blast launchers instead of 8, and adding a third set, gives 4800 warheads, and 1.14g0 acceleration)
This is essentially equivalent to a Corvette, with no FTL drive, two picket weapon slots and two missile weapon slots.
It is extremely expensive based on the game's economic assumptions, especially when you maximise the amount of nukes on board; 4800 anti-ship missiles are not cheap.
But, keep in mind that the expensive part is the Plutonium-239:
As discussed up-thread, Life2.0 has vastly cheaper access to P-239 than we do - their society is literally built on widespread nuclear proliferation, where every family has state-subsidised access to at least one breeder reactor passively producing Pu-239. (no dumping nuclear waste here, it all gets reprocessed and the P-239 obtained through transmuting Uranium-238 goes into bombs, and their 1kt Pu-239 bomb uses 104 grams of the stuff)
This, of course, examples exactly why in our world we don't reprocess spent fuel rods and instead put them underground, because if terrorists had access to this kind of a setup...
So, between setting up an industry that mass produces these things and has vastly cheaper access to the raw materials, we can drop the Pu-239 cost massively. The second most expensive part of these bombs is that I never actually bothered to change the fast explosive away from the second most expensive option of Octogen, or adjusted the fuel tanks to reduce missile delta-v back down to the original missile I duplicated to start with, etc. (for what it's worth, tweaking these variables and fine-tuning the rest of the system drops our cost by about six million in-game credits, adds 3200 more nukes, with each one doing slightly bigger explosions because of their own increased explosive amount, but, adds slight mass increase and therefore a 2km/s reduction)
This ship is still optimised on the assumption of launching from Unity, hence why it has a relatively high acceleration value. (my own preference is that I have a minimum of 0.2g, otherwise I go back and add more thrust; 0.2g is what I consider just about passable acceleration for Kerbal Space Program, and also represents a healthy thrust/weight ratio for SSTO from Luna launches) 40km/s is perfectly adequate for inner-star system operations - that's enough delta-v to tour every planet out to Jupiter in the Sol system - but even with a hyper drive attached, it's not going very far.
It needs a Refueler.
This is where the bigger Orion drives come in very handy - a Refueler built with the 26m pusher plate and the same launching from Unity requirement has just enough payload mass to refuel the Corvette. And then need refuelling itself because of the barely planet-escaping acceleration of 1.06g. (as said though, there's margin for it as the surface-to-orbit nukes can be smaller)
By contrast, the 150m pusher plate Refueler can carry enough nukes to extend the 26m Corvette's delta-v out to well over a million km/s.
Stellaris of course totally abstracts Refuelers.
My extrapolation is that a ship would need a minimum 200km/s to cross a Stellaris star system in a reasonable amount of time, although more would be preferable as that equates to several years of transit time. There is still a very long way to go though; a constant-acceleration trip to cover the same distance is where I got eighteen days from for the Flagship's transit.
So, what have we got?
Putting it into Stellaris terms, we are now definitely at the start of the tech tree, at least when based on the frankly ludicrious speed Stellaris' chemical rockets go at.
Just in time for the Olinbar to surrender their more advanced propulsion technologies, of course.
But... The laptop can't cope with Stellaris anymore.
Unfortunately...
12m diameter pusher plate ships are essentially too small to fit into Stellaris' ship classification scheme. Which I'm not sure what to think of, given the Orion battleship Kennedy saw a model of and cancelled the project used the 26m pusher plate we'll look at now:
26m pusher plates are Corvettes:

This one represents a Planetary Defence Corvette. 26m pusher plate, small shuttle pod bay, 2x 50MW lasers for point defence and sub-system targeting, and 1600x 1kt nuclear warheads, of which hopefully at least one will get through enemy defences at detonate at point blank range and flood the enemy vessel with x-rays and neutrons. (an easy upgrade if you don't mind taking longer to get to orbit is bolting on more missiles, as switching to 16 blast launchers instead of 8, and adding a third set, gives 4800 warheads, and 1.14g0 acceleration)
This is essentially equivalent to a Corvette, with no FTL drive, two picket weapon slots and two missile weapon slots.
It is extremely expensive based on the game's economic assumptions, especially when you maximise the amount of nukes on board; 4800 anti-ship missiles are not cheap.
But, keep in mind that the expensive part is the Plutonium-239:
As discussed up-thread, Life2.0 has vastly cheaper access to P-239 than we do - their society is literally built on widespread nuclear proliferation, where every family has state-subsidised access to at least one breeder reactor passively producing Pu-239. (no dumping nuclear waste here, it all gets reprocessed and the P-239 obtained through transmuting Uranium-238 goes into bombs, and their 1kt Pu-239 bomb uses 104 grams of the stuff)
This, of course, examples exactly why in our world we don't reprocess spent fuel rods and instead put them underground, because if terrorists had access to this kind of a setup...
So, between setting up an industry that mass produces these things and has vastly cheaper access to the raw materials, we can drop the Pu-239 cost massively. The second most expensive part of these bombs is that I never actually bothered to change the fast explosive away from the second most expensive option of Octogen, or adjusted the fuel tanks to reduce missile delta-v back down to the original missile I duplicated to start with, etc. (for what it's worth, tweaking these variables and fine-tuning the rest of the system drops our cost by about six million in-game credits, adds 3200 more nukes, with each one doing slightly bigger explosions because of their own increased explosive amount, but, adds slight mass increase and therefore a 2km/s reduction)

This ship is still optimised on the assumption of launching from Unity, hence why it has a relatively high acceleration value. (my own preference is that I have a minimum of 0.2g, otherwise I go back and add more thrust; 0.2g is what I consider just about passable acceleration for Kerbal Space Program, and also represents a healthy thrust/weight ratio for SSTO from Luna launches) 40km/s is perfectly adequate for inner-star system operations - that's enough delta-v to tour every planet out to Jupiter in the Sol system - but even with a hyper drive attached, it's not going very far.
It needs a Refueler.
This is where the bigger Orion drives come in very handy - a Refueler built with the 26m pusher plate and the same launching from Unity requirement has just enough payload mass to refuel the Corvette. And then need refuelling itself because of the barely planet-escaping acceleration of 1.06g. (as said though, there's margin for it as the surface-to-orbit nukes can be smaller)
By contrast, the 150m pusher plate Refueler can carry enough nukes to extend the 26m Corvette's delta-v out to well over a million km/s.
Stellaris of course totally abstracts Refuelers.
My extrapolation is that a ship would need a minimum 200km/s to cross a Stellaris star system in a reasonable amount of time, although more would be preferable as that equates to several years of transit time. There is still a very long way to go though; a constant-acceleration trip to cover the same distance is where I got eighteen days from for the Flagship's transit.
So, what have we got?
Putting it into Stellaris terms, we are now definitely at the start of the tech tree, at least when based on the frankly ludicrious speed Stellaris' chemical rockets go at.
Just in time for the Olinbar to surrender their more advanced propulsion technologies, of course.