

There is a mix of very precise issues with very detailed examples but also a thread of not being “comfortable” which makes it challenging for me to make practical suggestions.
If that’s OK I’d suggest to start with the top 5 problems you have then I, and hopefully others, can give potential paths forward.
One generic advice though the learning curve might feel threateningly high but I’d argue it’s if you consider this a short term adventure. If you think about the next year or so, discovering the intricacies of a distribution or shortcuts for a desktop environment look like a bad investment of your time. If now you consider this, especially as you mentioned managing servers for years, relying on WSL, etc a long term investment. If you imagine than in 10 years, heck even 50 years, console, servers, VR headsets, desktop, phones, tablets… all run Linux (which to be clear basically is the case now, even before the Valve recent announcement) then it’s a totally different dynamic. I don’t mean “behind the scene” kind of things, I mean today you can use adb shell on your standalone VR HMD, on your video projector, on your phone, etc. You can also have the console on your Mac laptop. It doesn’t make learning easier, it’s just a lot more motivating IMHO.
Also on that topic, my “trick” is to write down notes. It can be actual notes or just my ~/.bashrc or ~/bin in a more pragmatic day to day solutions. They do add up, day after day, years after years. Each challenge once overcome can be composable and a new opportunity to do more.

At uni I logged on a thin terminal that would then connect to a computer with hundreds of users.
You think of your computer as a desktop but in a reality it can be a lot more than that. Hundreds of users could simultaneously use it without bothering you (assuming resources are sufficient).
Obviously that also means you shouldn’t be able to see or edit files from other users
You, like most of us to be clear, are just using it in a very very limited way.
It costs pragmatically nothing to keep this model working and it seriously limit usage to remove that. Now if you do want, you can autologin and skip all this but at your own risk.
TL;DR: a desktop is just a server with a screen, mouse and keyboard, nothing magical about it. If a server can handle hundreds of users, so can your desktop even if that’s not how you use it.