From what I read - there's a remastered version that includes the DLC which is prominently advertised since March this year (which is also the version coming to Humble Choice). The remaster apparently had huge performance issues, but those have been (recently) resolved after few patches. Seems like typical AAA "We'll fix it" behaviour, sadly.
Remarkably is that buying that remastered version doesn't provide a copy to the original (probably due to IP ownership lying with Obsidian/Microsoft than Private Division themselves).
To add to the folks owning both a Switch and a Deck:
Keep in mind that the Steam Deck might be more "unstable" than a regular console like a Switch. Not just games or controller config tweaks, but also general system stability - I'm speaking of experience with the beta software of the Deck.
Despite that, if you're tech-savvy enough or are happy to stick with only Verfiied/Playable rated games without tinkering, the Steam Deck's highly recommendable. Even for party games, as you can just use any vendor's controller on the Deck basically. Don't need to get 4 of one vendor or the like.