The new iichid input stack can handle the volume keys on audio devices, which is preferred when something in the desktop environment reacts to them :) so it should be possible to disable uaudio's built-in handling.
([[ https://github.com/wulf7/iichid/issues/46 | also iichid currently doesn't avoid attaching when uaudio has attached ]] but that's an orthogonal issue: when it's fixed, uaudio would still get priority — so I want to be able to switch to iichid's handling with this tunable)