I feel like this would fit in some unexpected areas of mobile computing. Music, interfacing with other equipment (e.g. industrial computing), or other places where people might normally take a full laptop where that's kind of overkill.
I'm not really sure, and I kind of wish I had a need for one.
I think it's for the Hacker News crowd that's always clamoring for smaller phones, or phones with a physical keyboard. Potentially for parents to give to their young children, to be able to contact them without getting them addicted to screens right away.
I feel like if the people who make raspberry pis made a phone (or phone components, mainly the board) I would buy the hell outta that bitch. This sounds kiiinda like that but idk that I actually trust it.