Welcome to the Community forum.
Also following and getting involved in the /e/OS community is very recommendable 
(I am an /e/OS user myself, although still on an FP3).
/e/OS usually comes with a fork of OpenCamera as its default camera app. Only last year, /e/OS was for the first time ever able – with Fairphone’s help – to also offer Fairphone’s native camera app on the FP4 and then the FP5. Fairphone is known to pass on firmware patches and the like to /e/ development for Fairphones, so if Murena should be able to offer Fairphone’s camera app for the FP6 at one point as well (I take it from your report that this is not the case right now), it would most likely also get future camera app updates from Fairphone with a little delay.