We are currently working on a title for Quest and we seemingly cannot have Fixed Foveated Rendering and any post processing in our game.
The summary of our issue is that we would like the option of applying dynamic bloom within the game on platforms (Quest 2) that would possibly have the GPU head-room to allow it. At the moment we cannot determine if we have the option, because we are unable to enable FFR whilst also enabling bloom via Unity URP's default Post-Processing.
As far as I am aware, any additional blit carried out by URP's pipeline disables Oculus' FFR, meaning we cannot gather the performance data required with both enabled to determine if it is a viable possibility. We're posting here as we can't find any other instances on this forum but it seems this is a known issue over on the Unity forums, but are not sure of the solution, whether it requires a custom bloom implementation on our part, a modification of the URP pipeline, or if the problem can be resolved within the Unity Oculus XR package.
We are using Unity Version 2020.3.0f1
There was a really good Oculus Connect 5 talk about porting to Quest that goes into the cost of doing post processing effects:
At about 10 minutes the speaker goes into detail of why post processing is so expensive on mobile hardware.
So even if the FFR-breaking blit was fixed it would probably be too expensive to do a standard post-processing bloom.
I would really, really love it if that blit issue was fixed though. URP has so much potential, but has had so many blocking bugs for mobile Oculus platforms.