I, too, like others in this thread had the infinitely loading bug on macos (not an M2 mac in my case), and I too wasn't able to fix it by deleting the launcher in the Application Support folder. I did, however, manage to figure out why: for it to work I had to *restart steam after deleting the launcher* (and before trying to launch the game — which would reinstall the launcher). Writing it here because this is the first result on google when searching for help. On that note, AndrewT, it would probably be helpful if you could edit the first post in this thread in which you gave instructions on how to reinstall the launcher to mention restarting steam too, as I am sure there are others who search for help here, but perhaps don't read all the way through the second page.
Also interesting is that the problem appeared in the first place after I restarted steam earlier today (for the first time in quite a while).
Unfortunately I neglected to back up the logs before deleting the launcher, but what I can tell you is that there did not seem to be any anomalous entries in them.
The last entry in the bootstrapper and dowser logs denoted success, so those components probably worked as expected, while the launcher log stopped at "2024-08-07T19:13:17.110Z (pid:53025) info [Game container]: Game dist platform: steam" (this line taken from the log now that it's working, but I remember this being the last line while it didn't work, just with a different timestamp and process id of course).
One more note: this is at least the second time this happened to me. I remember having this problem another time, though at more than a year ago I believe (and not well enough that I didn't still have to search around for solutions for an hour).
P.S. I hadn't actually tried simply restarting steam without deleting the launcher — it is possible that it was purely some internal state in steam that was corrupted (or, you know, unexpected somehow) and the launcher was perfectly fine (except for relying on this apparently-untrue assumption about the state of steam).