> My problem is the ARM chip and how likely I am going to have problems running a non-blessed OS on the thing.
ARM shouldn't be a problem for a long time; there's a huge number of boards out there using that architecture and most of them are well supported by Linux.
Here are some Armbian images: https://users.armbian.com/balbes150/opi800/
The user is reliable and a regular Armbian contributor/maintainer.
> zero real applications for the thing other than a cute novelty
I think the main selling point of these devices is for kids to carry them in their backpack when they study with their friends, so that they have all their stuff in a single device that is more usable and safe than a cellphone and needs only a video connection, without messing with the family computer.
A relatively low cost independent device with exposed gpio ports could also have some uses in a lab to drive external hardware, microcontrollers programming, etc. If I had one I would probably use it for such tasks, including audio measurement by adding an external sound card.