This feature request is not for the SDK but rather for the OS. Not sure this is the right category or even the right website where to post this, so feel free to point me towards the right direction if needed.
What I'd like to see in the Settings menu is an option to adjust the crank offset/drift. My idea would be a 4-step process where you are asked to turn the crank and press A at the real/expected 0°, 90°, 180° and 270° rotation. The OS would save the difference between each rotation and the magnetometer reading at those rotations, then provide an interpolated result to the input API.
I'm asking this because I noticed my PlayDate wasn't reporting the correct crank position when pointing it perfectly downwards. I went to the Input Test and sure enough the reading was wrong: what should have been 0°, 90°, 180°, 270° became 0°, 86°, 173° 266°. I think it's normal for the magnetometer to drift like that, but it's annoying with games that use the absolute crank rotation. I believe this solution would mitigate the issue noticeably!