OpenTTD.
Aren’t all of these things basically out-of-band investments? They didn’t recontribute upstream to these projects from what I understand
Maintaining a fork is not mutually exclusive with contributing changes upstream. Valve’s policy is to upstream everything.
This shouldn't come as any surprise to any longtime Phoronix readers and dedicated open-source/Linux enthusiasts, but Valve with their work on the Steam Deck and SteamOS have been lifting the open-source ecosystem as a whole