> and are truly open in the sense that they are controlled by the user.

I don't see them altering the permission model, you probably meant the possibility of modifying the system by tools such as Magisk, which indeed make it possible to install software much less restricted..

.. but you can do that on any device with an unlockable bootloader. Graphene/Lineage only remove some Google spyware.

Try to install a Lineage phone app on GrapheneOS to understand what I mean :)