Well ultimately its also just a russian nerd building a nice program, but I get where you’re coming from. Good luck with your search and hopefully you’ll find what you’re looking for.

I also felt that way first but ultimately resigned as I couldnt find a decent alternative. Just curious, are you concerned about spyware/potentially malicious updates or do you just want to be sure/free of proprietary software?

I use AIMP. My Library has roughly 6k files, it has replay gain and mostly when I add new files it notices it automatically and includes them in the library relatively quickly. You can also choose to manually scan for just tag or cover changes. And as a nice bonus, there are a few user made themes you can use to customize the look of the app. My only critique of the app up to date is, that the audio suffers a bit when using volume boost and that the ui requires a bit of learning how to use it.

If you like 2D platformers there are cats are liquid, cat bird and slime labs. Besides that, Progressbar95 is also fun

On any Fedora based distro you can quite easily install the proprietary nvidia drivers (this is necessary for a good experience btw). For windows programs you could take a look at winboat, it basically spins up windows in docker and it doesnt need any configuration whatsoever. For an animated wallpaper, KDE Plasma has a wallpaper engine plugin. Its a bit fiddly as I remember and not every wallpaper works, but its good enough for me.