I can't find the link, but there was some discussion from the graphene developers about needing some data that they couldn't get from fairphone. I searched the GitHub issues but I couldn't find it. Maybe it's in the forum.
Interestingly fair phone forum blocks my country, saying data is not available in my country. Doesn't sound very fair to me
-- update https://github.com/GrapheneOS/os-issue-tracker/issues/820#issuecomment-978253711
Found the link, but graphene has deleted the issue. That might mean they're actually working on fairphone. But that's just me guessing. But yeah if you dig it up in the archive, you'll see they're talking about they couldn't get the right data from fairphone. But that was a couple years ago. Maybe things have changed