- Edited
To confirm - its still an issue and I don't think it will be fixed anytime soon.
As already discussed, the root cause is that Google Camera does all the processing on its own and uses special SELinux domain for hardware acceleration. That SELinux domain is removed in GOS for security reasons.
So the only way to make it work is either GOS team bringing it back (which they confirmed they won't) or Google fixing their Camera app to change the SELinux domain (which they say they are working on but its been months and months with no progress so its most likely never be fixed).
GOS camera (and any other 3rd party camera) are using the same (restricted) API that lacks all the processing Google Camera offers hence the quality is not comparable. It doesn't matter what 3rd party Camera app we will use - they all use the same API so the quality will be more or less the same (and not good vs Google Camera).
Maybe if many people ask GOS developers, they will consider to implement a toggle or something similar that will enable SELinux domain in Google Camera with user accepting potential risks associated with this. I am not a developer so not sure if this is a feasible option but maybe it will be possible to implement a toggle?
Currently, Google Camera is really slow in processing images, especially, portrait pictures or when taking multiple pictures at once.