Very hard, out of like 250 games only 1 wouldn't boot up not matter what I tried and it was a very niche indie flash game. Though it was a while ago and maybe the new versions of proton fixed even that.
I'm not sure what you're commenting on. I just think it's odd that they wouldn't label it as playable when it is playable. I guess Steam doesn't have the time to check all of their top 100 games for the month. That seems like a lost opportunity to promote their device.
I know when I see all of the "unsupported" games on here, it makes me not want to get one. If most of them said "playable", as you say they are, then it would seem more worth it.
I’m saying it also works for games outside that scope. Things that aren’t deliberately checked and don’t have enough player reporting to justify switching the tag.
The biggest reason games don’t work on Linux is 3rd party bs.