Switch games aren’t designed for toddlers, by and large.

I’d just recommend a bright, cheerful game that requires little to zero reading and keeps to simple mechanics: New Super Mario Bros games, Mario 3D World, Mario Wonder, Yoshi’s Wooly/Crafted World, DK Tropical Freeze, Kirby Star Allies (Forgotten Land might be a bit more difficult or “dark” in tone for a toddler). You might find some good games that work on the eShop too.

Doom Eternal. Time to rip and tear, toddler!