There was a WiFi app that did that forget the nameSo you can play it like a Switch in Tabletop mode?
That link is dead now.You activate input redirection in Rosalina, and on the PC you run a client software, that sends the commands to the 3DS.
https://www.sthetix.info/tutorial/nintendo-3ds/how-to-use-xbox-one-controller-on-nintendo-3ds