Unfortunately the camera app is quite a bit worse in my opinion (used it on the OnePlus One, 3T and haven't tested it with my 5). Guess some things are more important at this point..
Is there no way one can extract the oneplus camera app and install it on lineageos? I'm also going to finally switch now, but I don't understand why there isn't some clever hacker that has done this yet. Is is impossible?
To gain root access you have to flash an optional zip file [0] after flashing LineageOS itself and the also optional OpenGapps [1]. If you don't do that, your Boxer app should pass these SafetyNet checks [2].
If you want both root and still full access to these SafetyNet-"protected" apps, you can try the alternative rooting solution Magisk [3] which specializes on bypassing these (imho arbitrary) restrictions.
My bank app refused to install on a rooted phone. I used Magisk Manager to work around that. I guess it could work in this case as well. There is a 'hide root' option (or something similar).
Unfortunately the camera app is quite a bit worse in my opinion (used it on the OnePlus One, 3T and haven't tested it with my 5). Guess some things are more important at this point..