I'm very happy for graphene and motorola, and hoping this comes to less premium lines!
One of the most exciting things is that GrapheneOS folks insist the bootloader not be locked. I continue to think actual Linux on the phone is kind of just waiting for us, that it'd be imminently possible. If we had some modern-ish devices with unlocked bootloaders. Especially if they are Qualcomm chipsets, which have been seeing a lot more linux upstreaming/mainlining support than any other ARM platform. https://news.ycombinator.com/item?id=49361686
GrapheneOS requires the bootloader be locked for a complete install. But it does require the bootloader be unlockable and support yellowboot.
GrapheneOS, Android, and android based OSs, are all linux distros.