@PurpleLibraryGuy

I'm a little unclear what you're supposed to do with the controller bits once you pull them off. Do you stick them together? That would be weirdly narrow. Do you just use them as separate bits, one in each hand?

Yes, one in each hand, rest your hands wherever: on your lap, on the back of the couch, to either side of your body, on top of your head. It's very comfortable and freeing and makes gyro mouse very simple.
At risk of exaggeration, the "tyranny of controller design" locks out hands together and our shoulders and arms in a certain position. Split joycons like these permit you to adopt any comfortable position you like. No shoulder or elbow strain!