I think you're 100% on the right track with the evdev-no-grab, but while I was getting the controller configured correctly in the system, I did something that just deactivated the spinner completely.

I'm going to crash for the night, but will continue to bash my head against this tomorrow. I'll let you know what I come up with.

I found this Atari controller config file. Can this be used to help? Obviously, I am not too savvy with this. I have figured out some basics with Mame on the PC, but struggling to translate everything into RP emulators. I can get the game to play with a mouse on some versions of advmame and Lr-mame, but when using the original 720 joystick I can only get the skater to very quickly flip back and forth 180 degrees. The mouse buttons I have connected to the Optipac with the joystick can be mapped, but not the joystick..Hopefully using Pastebin correctly...Appreciate any help I can get. Thanks!

https://pastebin.com/H1vB0iRX