I recently noticed, that another planned Linux phone Librem 5 was announced. And as part of their presentation they released a video, which you can find on their web:
https://puri.sm/shop/librem-5/[/url
Not a fan of Gnome — I adhere to the TDE fork of KDE — but what is listed at the link you provided is fascinating, because it suggests a Linux-only boot and a privacy-based phone OS. I wonder if all this will be open source. Because but for the telephony aspects, I would seek to be utterly and entirely free of Android, which is in my estimation nothing more that a Google spyware operating system (as opposed to IOS, which is nothing more than a very slick Apple spyware operating system). Given a pure Linux that does phone calls and I would hasten to nuke whatever comes on the Gemini and replace it.
One of the reasons I hope the Gemini is very successful is that skilled persons would then be likely to do a comprehensive security audit. As it is, I fear (though without evidence one way or the other) that whatever bootloader lets us boot Linux will include a layer that ships our information to Google. But I may be overly concerned in this regard.
Meantime, the Debian ARM repository includes Gnome, does it not?