jakibaki has released an updated version of his Gameboy Colour Emulator for Nintendo Switch
Since retroarch isn't working on anything higher then 3.0 right now I ported the gameboy color emulator khedgb to the nintendo switch. (Works on all versions as far as I know)
Right now it doesn't have many features but it's enough to finally enjoy pokemon on the nintendo switch
Simply put the rom into sd:/switch/roms/gbc and start the homebrew.
This emulator can't detect when you used the ingame save-feature so you'll have to press the X-button every time after using the in-game save feature. Otherwise the save will get lost after restarting the emulator!
Please don't expect too much from this, I just made this so I could play pokemon and it's not going to get many features.
As soon as retroarch gets updated for 5.0 this will instantly become obsolete.
source (you need the sdl2-libraries from the devkit-pro pacman to build this)
UPDATE:
Added audio support and proper scaling! (Many thanks @cpasjuste for the scaling-hint!)
UPDATE2:
Fixed a bug where after saving the game for a few times the emulator would crash.
UPDATE3:
Added joycon-analog-stick-support!
UPDATE4:
Removed the debug log.
UPDATE5:
Added a simple file picker! You can now play multiple roms
UPDATE6:
Audio is much better now (not perfect yet though). Many thanks to @renhei for the fix-suggestion!
UPDATE7:
Changed rompath from sd:/switch/roms to sd:/switch/roms/gbc in order to avoid confusion with the gba emulator. Also double joycons now work in unattached mode!