K8y When Graphene updates its Operating System versions, does it do it more frequently for the newest pixel?
Not in general. If there is a specific problem for a new device that device might get a specific fix, but in general every release is for every supported device.
See: https://grapheneos.org/releases
End-of-life devices are updated more sporadically, but it is strongly recommended to not install GrapheneOS on an EOL device.