Forgot to post that this project has been updated to work on 2022+ GR86/BRZ.
The primary focus now is 2022+ cars, but it should still work fine on gen1 cars.
You just need to tweak one of the files to specify which car you have.
If you forget to do that, the code will fail to compile, and the error will nudge you in the right direction.
Demo from a track day in my 2022 GR86: