As for the Steam Deck they said they don't have the ability to test it right now, and it won't be coming to Steam until "we determine our ability to comply with Steam's policies".

There was an article in Rock Paper Shotgun today that clarifies this obfuscation:

https://www.rockpapershotgun.com/hytale-wont-be-on-steam-right-away-as-its-devs-want-to-avoid-overindexing-on-negative-reviews-from-players-who-arent-as-well-informed-yet [External Link]

In this interview, the producer and team lead, Patrick 'Lyall' Derbic, was asked if the game would be on Steam, his reply was:

"No, not initially," he wrote. "We want to spend our time in early access working with the community and improving the game, rather than overindexing on negative reviews from players that aren't as well-informed yet about what we are doing. Steam is a great marketing tool, but one that we might never need. This doesn't mean we will never be on Steam - just that we do not see the necessity of it yet."

This explanation makes much more sense to me.