The whole reason why GrapheneOS is superior to its alternative is because they do all that.

I also with they could support non-Google phones, but that's a problem coming from the manufacturers, not from GrapheneOS.

My understanding is that there are close to half a million GrapheneOS users. And many potential users don't want to buy a Google phone. So it feels like it is starting to become worth considering for manufacturers...

I don't get why Fairphone doesn't look into that. Is it because they are not aware, or is it too hard for them to make hardware that is compliant with what GrapheneOS requires? Hundreds of thousands of devices may not count so much for Samsung, but they must definitely count for Fairphone.