It's not a small team, but Valve seems to have a very similar proportion of employees to users. I think they have about 400 employees, and a user base of 140 million. That's roughly 3 employees per million users.
They’re running a marketplace though, and that’s a bit of a special case — obviously why VCs are always very excited for anything that is or looks like it might able to become marketplace-shaped.
Certainly there aren’t 140M MAU fore the steam deck or any of the games they’ve built themselves, that’s for sure.