It really depends on what security level you want out of a phone
It does, but that's exactly my point. GrapheneOS will provide you essentially no more security than any other alternative Android operating system, should it have to operate on a Fairphone with all those features not supported by a Fairphone stripped away.
Unless Fairphone adds more hardware security features that are standard on most other phones, and highly supported on Pixels, installing a heavily crippled GrapheneOS on a Fairphone would get you essentially none of the benefits of GrapheneOS in the first place.
All Android devices are supposed to support it, but not all do. (or at least, not all do effectively without compromising the cryptographic root of trust by not implementing proper hardware security chips)
I'll grant it to you on the scopes, PIN changes, etc, but realistically I just don't think anyone can justify GrapheneOS being something that should be supported on Fairphone given how absolutely desolate the phone looks with regard to any attempt at all to hardware security.