My library is plenty large enough and it’s 80%+ gold verified on protondb, and I’ve found success in running titles that were unverified (but not borked, I’ve never tried any of the dozen or so borked games in my library).
Disgaea 4 runs flawlessly without any modification on my deck, it does take a moment to start, I believe that is when it’s trying to connect to the online servers which I have entirely disabled through the in game options menu.
I won’t attest to anything outside of steam, because I didn’t buy a laptop or a console, I bought a steam deck. And I have more than a thousand games ready to go on it.
Edit to add: not sure where you pulled “universal compatability” from, I never mentioned that at all. Contrary to that statement all of the games I mentioned, and everything I’ve ever tried playing, are titles activated through steam.
Yet still people will find reason to complain.
80% of my catalog is platinum and gold, 20% I probably wasn’t going to play anyways.