I have at least 3 SD cards that I regular use on my switch. One card is for minor games, another for big adventure games, another for sports games.
The setup is pretty easy: all the usual folders except for the Nintendo folder (meaning atmosphere + hekate +
sigpatches + switch folder with selected homebrews)
Make a custom bootlogo for each SD card and you're all set
Once you boot the newly setup card, game icons will have a cloud icon meaning they're not installed on that card. You need to install new games then (you can reinstall any game you wish on your previous card also because why not?)
To only see games on that SD card, go to settings- manage data. Games with filesize are the ones.
Conveniently you can install blawar's tinfoil 11 and sort games according to size and launch them from there.
Hope this helps