A switch port for Kingdom Hearts collection could come maybe after the xbox version, but as for Kingdom Hearts 3 some information has been given in the past saying that square enix is interested in the idea but an ex gameinformer employee said that he got reports it wasn't working out getting the game running on switch, but square enix got Dragon Quest 11 working on switch which also runs on unreal engine, even though they had a good number of issues getting it onto switch but that was because it was an older version of unreal that switch couldn't support if i remember correctly. So anything is possible but i just don't know when, plus they might want to focus first on a possible PC port first if anything.
https://comicbook.com/gaming/2019/02/17/kingdom-hearts-3-nintendo-switch-release/
