MasterFeizz has ported the Nintendo DS Emulator for Switch, heres release news:

The last couple of days I decided to mess around with the switch, so for my first release I decided on a DS emulator.

The interface is very crude based on the Vita port I worked on a few years back. Basically just put some roms inside sdmc:/switch/desmume/roms and play.

download https://github.com/masterfeizz/DeSmuME-NX

via http://www.nintendomax.com/viewtopic.php?f=168&t=16570