Comment by bsimpson

FWIW, I have submitted a couple small patches to get the display and gamepad for my Lenovo Legion Go recognized correctly - probably similar levels of complexity to your change. One was to input and one was to display quirks.

They did take months to finally land, and the whole process of getting my corp email address to be compatible with their email-based PR system was way more of a faff than it had any right to be, but they did land. You can install mainline Linux on a Legion Go now and the display and controller will behave as expected, out-of-the-box.