Totally different animals. De-googled Android (including GrapheneOS) is easily a daily driver if you can avoid Google services by finding alternatives.
The Pinephone is totally a beta product and so far only one of the distros I've tried works properly.
They state this clearly when you buy it so it's not a criticism, just saying it's not an alternative to Android, it's not ready for daily use and definitely not ready for normies.
Meanwhile I put GrapheneOS on my gf's phone and she can use it fine and she's not a tech nerd at all.
Pinephone is for trying out cool new shit that won't work 100%.