What would that look like? A first thought would be a controller with storage that would 'dock' into various screen sizes and case molds?

https://github.com/iandchasse/de-link

Someone is working on a more DIY device that can run this firmware.

TRMNL are kinda.

https://trmnl.com/

supernote's tablets are designed to have replaceable motherboards/batteries although it's still to be seen whether they will actually be able to support that long-term.