I'm assuming since the Steam Deck push it's all changed. Either way, I don't tend to play AAA, but I've been able to play all the games I've wanted to without issue in Steam.

Many games run acceptably well on Linux nowadays thanks to Valve's efforts with the Steam Deck, pushing technologies like Wine -> Proton and DXVK.

The biggest chunk of games that do not work falls into the multiplayer / live-service category, as anti-cheat solutions often don't allow for running on Linux this way.

Compared to macOS, this is probably night vs. day.

I think since Steam has been working so hard on Steam Deck and SteamOS the compatibility has skyrocketed to pretty much parity with Windows