/e/-OS includes a modified version of OpenCamera that is installed as part of the system and has the SYSTEM_CAMERA permission. Only with that permission it’s possible to use the Wide Angle camera. e / os / Camera · GitLab
User-installed camera apps are unable to use the wide angle camera. That’s not really a bug but was done that way by design. Not sure how common this is. On a Pixel Phone, can third party apps use auxiliary cameras?
The part that defines which camera is a system camera is closed source, unfortunately. Fairphone should change this to make everything accessible by all apps.
Another thing is that some open source Android components seem to be modified with Fairphone specific proprietary extensions (i.e. libcameraservice from camera · ks-aosp.lnx.3.0.r4-rel · CodeLinaro / la / platform / frameworks / av · GitLab). Fairphone could release that modifications as open source, but due to Apache 2.0 License there is no obligation, unfortunately. That mostly matters for custom roms.