Librem 5 (https://puri.sm/products/librem-5/) is doing just that, a standard linux phone running standard linux apps with upstream drivers.
Most of the software effort going into librem 5 could be directly applicable to this. The barrier will be any proprietary drivers in the fairphone, but there is a lot of opportunity for their efforts to be very complimentary.
Is it possible to run more ethical software that doesn't track you? (not google-based android)