What about Valve itself? They have ~350 employees. They make Steam, SteamOS, Steam Deck, Steam Machine, Steam Frame, the Source engine, and run four actively successful live service games: CS2, Dota2, TF2, Deadlock.
The small size of Valve is simultaneously mind boggling but also not, given its very intentional independence. I would have to imagine that they must contract out or have partners at least for their hardware relationships if not for their massively multiplayer online games. At just 350 people that's enough annual revenue to make everyone there a millionaire several times over. Simultaneously plausible but mind boggling.
Yeah but Valve is not publicly traded, so that comparison is of course totally unfair! /s
Having skilled and happy employees that aren't constantly changing and do not spend all of their time on ways to fuck over customers and chase trends is simply impossible. Releasing a piece of hardware and leaving it open for customers to do with what they want? Linux? Not hiring people the second line goes up and then immediately firing them when line stagnates? Preposterous.
Last I've heard Valve makes use of a lot of contractors however. So the number of people working on their projects is a bit higher than their employee count suggests. Anyone's guess how many though.
I know they're sponsoring a bunch of ARM and Linux projects as well.