Epic games has its own store: its competing. There is no way they want to support the steamdeck right now. Same goes for xbox/Activision in a lot of ways and anything they're doing for the time being is just a way to sedate the law makers that objected to M$ activision acquisition.

Going to add that Epic Games blaming engineering headcount is a BS measure to distract from it too. They just got done suing Google. They absolutely want every part of the bottom line they can grab. Many companies have cut/are cutting programming staff to hedge bets they will be fully replaced if not mostly replaced in 5-10 years.