SteamOS can really only be a good thing for devs, as I understand it. The steam deck gives them fairly limited hardware to target for development if they’re inclined to do so, and Valve’s effort with Proton have done wonders for general Linux compatibility, even in the absence of a native Linux version of their games. That’s opened up a sizable market for them that was previously unavailable.
Despite growing up in the 90s, a Commodore 128 was the only computer we had until maybe 1998, when we upgraded to some sort of Macintosh. It was just Frogger, Montezuma’s Revenge and OutNumbered! for me on computers until we finally got a Dell of some sort running Windows XP in like 2004.
I got all the pain of different OSes growing up, but now it’s just Linux and OpenBSD for me these days.