Some of these have popped up on here from time to time, but I decided to compile a list of *all* of the first-party/Nintendo-Published titles with demos on the (North American/US) Switch eShop. If you were looking at any of these titles but weren’t sold just yet, I hope this helps:
* [ARMS](https://www.nintendo.com/store/products/arms-switch/)
* [Big Brain Academy: Brain vs. Brain](https://www.nintendo.com/store/products/big-brain-academy-brain-vs-brain-switch/)
* [Boxboy! + Boxgirl!](https://www.nintendo.com/store/products/boxboy-plus-boxgirl-switch/) (*Added by test123455676*)
* [Bravely Default II](https://www.nintendo.com/store/products/bravely-default-ii-switch/)
* [Cadence of Hyrule: Crypt of the Necrodancer Featuring The Legend of Zelda](https://www.nintendo.com/store/products/cadence-of-hyrule-crypt-of-the-necrodancer-featuring-the-legend-of-zelda-switch/)
* [Captain Toad: Treasure Tracker](https://www.nintendo.com/store/products/captain-toad-treasure-tracker-switch/)
* [Clubhouse Games: 51 Worldwide Games](https://www.nintendo.com/store/products/clubhouse-games-51-worldwide-classics-switch/)
* [Daemon x Machina](https://www.nintendo.com/store/products/daemon-x-machina-switch/) (*Added by test123455676*)
* [Dragon Quest Builder 2](https://www.nintendo.com/en-us/store/products/dragon-quest-builders-2-switch/) (*Added by Dukemon102*)
* [Dragon Quest XI S: Echoes of an Elusive Age – Definitive Edition](https://www.nintendo.com/store/products/dragon-quest-xi-s-echoes-of-an-elusive-age-definitive-edition-switch/) (*Added by Dukemon102*)
* [Fitness Boxing](https://www.nintendo.com/store/products/fitness-boxing-switch/) (*Added by test123455676*)
* [Fitness Boxing 2: Rhythm & Exercise](https://www.nintendo.com/store/products/fitness-boxing-2-rhythm-and-exercise-switch/)
* [Game Builder Garage](https://www.nintendo.com/store/products/game-builder-garage-switch/)
* [Hyrule Warriors: Age of Calamity](https://www.nintendo.com/store/products/hyrule-warriors-age-of-calamity-switch/) (*Added by SocranX*)
* [Kirby and the Forgotten Land](https://www.nintendo.com/store/products/kirby-and-the-forgotten-land-switch/)
* [Kirby Fighters 2](https://www.nintendo.com/store/products/kirby-fighters-2-switch/)
* [Kirby Star Allies](https://www.nintendo.com/store/products/kirby-star-allies-switch/)
* [Mario Strikers: Battle League](https://www.nintendo.com/store/products/mario-strikers-battle-league-first-kick-switch/) (*Added by test123455676*) (*LTO online demo*)
* [Metroid Dread](https://www.nintendo.com/store/products/metroid-dread-switch/)
* [Miitopia](https://www.nintendo.com/store/products/miitopia-switch/)
* [~~Nintendo Switch Sports~~](https://www.nintendo.com/store/products/nintendo-switch-sports-switch/) (*Added by test123455676*) (*LTO online* d*emo, not currently available*)
* [Octopath Traveler](https://www.nintendo.com/store/products/octopath-traveler-prologue-demo-version-switch/) (*Added by GroktheDestroyer*)
* [Pikmin 3 Deluxe](https://www.nintendo.com/store/products/pikmin-3-deluxe-switch/)
* [Pokémon: Let’s Go, Eevee!](https://www.nintendo.com/store/products/pokemon-lets-go-eevee-switch/)
* [Pokémon: Let’s Go, Pikachu!](https://www.nintendo.com/store/products/pokemon-lets-go-pikachu-switch/)
* [Pokémon Mystery Dungeon: Rescue Team DX](https://www.nintendo.com/store/products/pokemon-mystery-dungeon-rescue-team-dx-switch/)
* [Pokken Tournament DX](https://www.nintendo.com/store/products/pokken-tournament-dx-switch/)
* [Snipperclips — Cut it Out, Together!](https://www.nintendo.com/store/products/snipperclips-cut-it-out-together-switch/)
* [~~Splatoon 2~~](https://www.nintendo.com/store/products/splatoon-2-switch/) (*Added by test123455676*) (*LTO online* d*emo, not currently available*)
* [Sushi Striker: The Way of Sushido](https://www.nintendo.com/store/products/sushi-striker-the-way-of-sushido-switch/) (*Added by test123455676*)
* [Triangle Strategy](https://www.nintendo.com/store/products/triangle-strategy-switch/)
* [WarioWare: Get It Together!](https://www.nintendo.com/store/products/warioware-get-it-together-switch/)
* [Yoshi’s Crafted World](https://www.nintendo.com/store/products/yoshis-crafted-world-switch/)
As always, I may have missed some, so put any others you find in the comments below!