For reference when Microsoft/Epic approaches the studios for games on their platforms they front the entire development cost. Sometimes millions of dollars. Google is just cheap and won’t invest in their own platform.
Direct quote: "We were approached by the Stadia team," one prominent indie developer told me. "Usually with that kind of thing, they lead with some kind of offer that would give you an incentive to go with them." But the incentive "was kind of non-existent," they said. "That's the short of it."
https://www.businessinsider.com/why-are-so-few-games-on-goog...