The Switch is an incredible console. Cuphead was good, but I felt like the way it handled multiplayer by more than doubling the challenge was less than ideal. I also got tired of the Gunstar dice-inspired section near the end.
Hollow Knight looks amazing, but the brutal platforming, mantis enemies, and punishing economy annoyed me after a few hours.
I recommend Towerfall and Rocket League for some easy to play/difficult to master fun on the Switch (or other consoles/Steam). Both games are fun by yourself, but get even better with more players.
I tend to prioritize physical copies games, especially if I can find a deal on a used copy. Otherwise, digital is more convenient.
I haven't tried Nintendo online, never appreciated playing against anonymous people. I have too many games to play and things to do IRL to bother with online gaming.