How to make a 3rd person camera
Greetings, and welcome to the forum! I hope that you find your time here to be positive! 
As to your question, first, let me ask: If you run the “device_tester” sample-program (which should be within the “gamepad” folder), are your joy-cons listed, and does the program respond to input from them?
If they are listed there, and if their input is shown, then the following manual-page should give you an idea of what to do:
(Or, of course, you could look at what the “device_tester” program does.)
Now, if your joy-cons are not detected by the “device_tester” program, then it’s possible that they’re not supported. In that case, you might want to post a request that they be supported in the Panda3D issue-tracker.