So I found a cool project on github which lets your computer emulate a switch controller. Check it out at https://github.com/mart1nro/joycontrol It's a dependency anyway. And was like, "I could totally pass a controller through to my switch from my desktop while logging the inputs in another program altogether. A few hours of coding later and here we are.
Your first question might be "Why the hell is this client server?". The answer was that I was running the server with a VM so that I could still use other bluetooth devices at the same time without worrying about messing up my environment. You know, since it involves modifying the bluetooth systemd service. I suppose you could run them off the same machine, but I'm not going to do that.
Download and install the original person's code and run the cli script to pair your switch. I'd recommend running it in a debian VM. Make the required changes to the systemd service of bluetooth. to start the server type python3 server.py $SWITCH_BT_MAC_ADDRESS.
Install inputs from pip. Run configure.py. I have nothing but contempt for the sort of imbiciles who make programs with non remappable buttons, so I made the effort. It's not perfect, almost on par with your average emulator, mind the lack of deadzones. It will create a file mapping your controller's buttons to buttons on a switch pro controller, and output a json file. Once you've got that, run client.py with the hostname of the computer where the server is running.
Neither the client nor server give any useful error messages besides throwing exceptions. I appologise. With that said, have fun with whatever you wind up doing with the code. Peace.