Software support is more important rather than open design, like the market for aftermarket for iPhone batteries is going to be much cheaper for them, so maintenance is cheaper, and because of project treble all newer Android phones will have mainline linux kernel support and have updated kernels, I don't see how Fairphone is more "open" compared to the alternatives or what you can do better when the volume of developers will matter for support more.
Software support is more important rather than open design, like the market for aftermarket for iPhone batteries is going to be much cheaper for them, so maintenance is cheaper, and because of project treble all newer Android phones will have mainline linux kernel support and have updated kernels, I don't see how Fairphone is more "open" compared to the alternatives or what you can do better when the volume of developers will matter for support more.