I'm currently using Bazzite with Steam's Big Picture mode, yes. I'd like to switch to Plasma Bigscreen, but I'm not sure it's ready just yet. I keep trying it on my laptop every few weeks, but there are some crashes I keep running into.

I can't wait to switch away from Steam Big Picture mode though, as it's pretty tedious adding shortcuts and having to use a Decky plugin to download art for them. It's very apparent that Steam isn't meant to be used this way (even though once you set it up, it's not bad). Plasma Bigscreen just reads the .desktop entries, which is a lot better.