You're going to want to install the Proton tools which include Wine and pile of other tools for making games work well (sometimes better) on Linux.

Besides installing Steam for Linux, you can also use Lutris which allows you a lot of tweaking to get non-steam games working under Proton.

You can check the viability of running your games on Linux with ProtonDB.

A shortcut to all this is to use a distro like Nobara or Bazzite that are pretty much designed from the ground up to run games and other graphics intensive software like video editors etc.

Heroic launcher with GE proton installed runs about anything that works on Steam Linux.

for games that fell off a truck or something, maybe look here. I've found almost all of those I've found in the mentioned way to work without issues with lutris.

as to upgrading the games, hadn't tried that. I know there are periodic updates for popular titles (like Cyberpunk 2077) released and you can find them in the same place you found the game, but seems too much hassle.

I've done plenty of installs for older games. I found using Lutris was easier than trying to do it manually, but it's not perfect (but it handles things like Proton, as another comment mentioned). It'll let you install games from their windows installers, so whatever games you've aquired should install as usual.

I think you can use Steam (for Linux) to manage Proton and your non-steam installs, but I haven't tried it.

Installing GOG games (without Galaxy) is about the same as what you're describing. The easiest way is with a game manager like Lutris, because it offers patched versions of Wine (like GloriousEggroll's builds), DXVK, vkd3d-proton, and various Windows libraries that the game or its launcher might need. Manually discovering and installing all that stuff is harder, but it can be done.

Yes just use Lutris. Depending on the method of installation you may need to either select the + and install from an exe file or copy the files over and then tell Lutris where the game's exe file is.

I actually don't have experience with this, but I've heard that all you have to do is use WINE and use the installers as usual and things should work out.

I'm considering doing the same actually so I'd be interested in hearing how this goes. I don't dual boot, but use Linux on my work computer and have just been using WSL on my home computer. Would be nice to get rid of the "gaming mode" Windows for my ADHD as well.

LinuxRuleZ makes repacks specifically for this. Has worked well with both Linux mint on desktop and bazzite on steam deck