To my knowledge there is no homebrew app that allows keyboard and mouse support on Switch, however some games natively support KBM - two off the top of my head being Hypnospace Outlaw and Fortnite where you can just plug a keyboard and mouse into the dock and the Switch will recognize it with no adapter. In terms of adapter I've seen the GameSir VX2 Aimbot online allowing keyboard and mouse in all games on Switch online by converting those inputs but can't vouch for it because I don't have one.Is there a homebrew app or something that makes kbm on switch possible? Kind of how adapters work, e.g. WASD=left stick