@luana@wetdry.world It will fully support using other operating systems including users making their own builds of GrapheneOS. It's part of our hardware requirements. We'll likely be able to make hardened builds of firmware and drivers which can be released in an official way for easy builds without needing to extract anything from the GrapheneOS or Motorola OS factory images.
Best shot is that EU will make it possible, as they distance themselves from US tech right now.