Iirc the chipset, QCM6490, will lose support after 2028 meaning the device will get at least 5 years of security updates and not the promised 8. Pretty sure that's why grapheneOS doesn't/won't support it since the company doesn't keep to their promises

Edit: found grapheneOS' response again I'm not saying Fairphone is a bad company but the way they are advertising the fp5 seems kinda shady IMO based on the specs of the device. At most you'll get partial updates after 5 years since Qualcomm will drop support which is still great but don't assume your device will be as safe as a fully updated device. Then again fairphone may commit to extending the life of the QCM6490 but not sure if they'll be capable of that so we'll just have to see. I apologize to anyone who got offended for some reason I was just expressing my opinion based on the track record of the company and the specs of their device