A tidbit from my interview:

Why is Fortnite still not playable on Steam Deck?

If we only had a few more programmers. It’s the Linux problem. I love the Steam Deck hardware. Valve has done an amazing job there; I wish they would get to tens of millions of users, at which point it would actually make sense to support it.

Epic’s own Easy Anti-Cheat does support Steam Deck, though — and both Valve and Epic agreed the anti-cheat part should be a simple matter in November 2021.