Back in January when it was originally mentioned of Collabora working on bringing PulseAudio to Android. That work has continued in the months since and now Arun Raghavan has a new blog post about this second part of his work.
To get audio playback working under PulseAudio on Android rather than AudioFlinger's "AudioTrack", the Google API was implemented to wrap around the PulseAudio client library. Arun says the playback side is about 80% done. "Basic playback works quite well" and he confirmed this with a video.
Thanks to this AudioFlinger replacement, it's also possible to take advantage of PulseAudio's remote playback capabilities:
This PulseAudio-over-Android work is still an early work in progress, but it's continuing to be worked on and financed by Collabora. They're also still bringing Wayland to Google's Android.