So, with all the wonderfully buggy stuff this forum is full of, time for another nuanced "this step is broken" with my problem -- it not being able to connect to Live to login.
So, I can get the launcher to launch. I can get the game to load, get to the "Press Enter to Start". I hit just about anything, it pops up the XBox Live login box, with the "[account name] Welcome back!" on it for my only MS Account, and the switch account/let's play buttons. I hit "let's play", it pops up a second smaller box that barely gets a chance to say "just a moment" on it, before it closes and the XBox Live login window goes, "We couldn't sign you into Xbox Live"... the problem I have with this, is that it's janky BS. It does this with the me being logged into the PSO2 site (which used Live to login) -- I tried it in the middle of writing this post, no less! -- and it does it with the XBox Game Pass PC app (which, when minimized to task bar, shows up as "Xbox (Beta)") running in the background (which wouldn't be able to load if it couldn't log into Live). It does it with the "Xbox Console Companion" app up as well, and with the XBox Game Bar up and running too, as I try to run up literally everything on my PC that would connect to this live account... and yet, PSO2 can't figure out how to do it, with or without these running.