There are many games only available on Switch. Most of the exclusives are published by Nintendo itself.
Mario
Since I like DRM-free stuff. GOG will be my first option.
Turns out many award winning games on Switch are also on GOG, vice versa.
Some games are available on Steam but not on GOG.
Majority of my must have lists are Square Enix and Bandai Namco games.
Some games are avaliable on console only