Google Pixel XL (marlin)
Android 9.0.0_r1
I'm pretty sure max said something about the DAC supporting Hi-Res but it isn't exposed in system.
This commit from Google shows otherwise:
https://android.googlesource.com/device/google/marlin/+/1299d9ec706b48221e82de8a6b994773ff87090c
Here's the present day audio_policy.conf:
https://android.googlesource.com/device/google/marlin/+/android-9.0.0_r1/audio_output_policy.conf