If you’re worried about bugs I think you should be able to get Mod Organizer 2 running on Steam Deck, and with all the various stability mods installed New Vegas runs fairly well. The Viva New Vegas mod guide is a great place to start, it should have most of what you need to get going.
I guess they wanted a change after Keshiks and Camel Archers being completely busted in Civ V.