Switch game to switch2

Hi, This is my first time buying a Switch. Now the Switch is finally not a 15fps slideshow; I just bought it, and it'll arrive later this week.

I don't care much for the new Mario Kart. I do want to play: -Mario Odyssey -Luigi's Mansion 3 -Breath of the Wild -Tears of the Kingdom.

These are all regular Switch games. I'm planning to buy game keys from G2A or something. Do I need to look out for something? I've heard something about upgrade versions? So how does this work?

Also, if anyone has more recommendations that I need to play, let me know.