Honestly, I'm not too sure how much price goes into it. I've used several of the Steam Deck competitors, each with better specs. But each has a worse overall experience. Each of the people I know with one of the competitors seldom uses it. But even the people with Steam Decks who planned to use theirs only for travel have ended up using them far more than they intended. My Steam Deck has become my primary gaming machine. I'm not sure how a hardware company competes there without working with a major game store, but I don't really see Valve being particularly opposed to working with hardware companies to provide Steam OS builds for competing hardware since it pushes their platform.

Personally, I don't think Epic is in a position to make a really feasible Steam Deck competitor, partially because they've gone all-in on Windows, and the break from Windows is one of the things that's allowed the Steam Deck to have its great experience. The only company who can really customise Windows to that extent is Microsoft, and they'd likely rather make an Xbox handheld than work with Epic on a Windows-based one.