I think Steam Deck is getting to be a large enough market that people are going to care about Linux support in the future (even if via Proton). It may be only 2%ish of the market, but I'll bet those 2% are the high-spending end of the market. The industry has reacted to the Deck by making everything work with it. That's not going to stop. Developers are not "only caring about Windows" any more.