alt Hacker NewsFairphone hasn't talked about GrapheneOS at all, instead opting to be in bed with Murena and /e/os, so I doubt they've even bothered to read the list of hardware requirements. They didn't bother with the Fairphone 6, which was released barely a year ago.
On the opposite, GrapheneOS team explicitly refuses to cooperate with Fairphone. See for yourself on their Twitter feed: https://nitter.net/search?f=tweets&q=fairphone+from%3Agraphe...