What are the requirements to play Kingdom Hearts on Nintendo Switch?
The following information is taken from Nintendo Support general FAQ regarding Cloud-based games:
What do I need to have except for a Nintendo Switch and the game to play?
Since the games are streamed through the cloud, you will need a consistent and stable connection to an internet source.
Do I need to have an online subscription?
No, you do not need Nintendo Switch Online services to purchase and play the cloud-based games, but you do need it to access and use any online features.