regarding the pixel 3a: there are patches in the pipe to make the second camera work as well - but there are still a bunch of issues to get ironed out. If anyone wants to play around, just install the following MRs with mrtest:
https://gitlab.com/postmarketOS/pmaports/-/merge_requests/5520
https://gitlab.com/postmarketOS/pmaports/-/merge_requests/5531
For a video see https://seafoam.space/objects/4d7c9ea7-d2fc-42d4-a7f0-8e953055a9d7