Steam just cracked 40 million concurrent users for the first timeโ , meaning Valve's user count was bigger than 80% of the countries in the United Nations | PC Gamer
https://www.pcgamer.com/gaming-industry/steam-just-cracked-40-million-concurrents-for-the-first-time-meaning-valves-user-count-was-bigger-than-80-percent-of-the-countries-in-the-united-nations/
I use it on my Steam Deck. It's limited as a general purpose OS but It's VERY good for gaming.
I'm pretty sure they run the entire gamut of eras, including new games... but it's the older games that people seem to be craving more, from what I've seen reported.