I guess Settings App -> System -> Feedback. But i think this is an OS feature request (like Jet in the other comment said), which is being handled by the manufacturer of the device you’re using instead of the actual AOSP. I’m not sure where you can leave feedback for AOSP, if that’s possible at all. Hope someone else can add that here.
Poor updates (policy), overpriced for the specs. I mean, 400-500 for a phone with a SD695 and 60hrz? Come on… Such a shame, because they are the only ones with a screen without a punchhole/camera cutout…