GrapheneOS is seemingly working with an OEM to make a GrapheneOS smartphone. Its probably not samsung, but would still be an established vendor

It better not be Samsung...

It isn't Samsung

I'd love this for a Fairphone.

They are not making a "GrapheneOS smartphone", they are just helping providers make their new devices compatible with the security requirements, so GrapheneOS can be installed on it. But GrapheneOS will not come by default AFAIK.