I have been looking into the Boox devices and the Supernote.
The more expensive Boox are, more or less, full-blown Android tablets. You should be able to install Joplin on them with zero issues. And now, they can transcribe your handwriting to text. And that text can be splatted into any text-consuming interface, like Joplin. So ... that should work. It would also be cool to make your hand-written notes into a PDF or image and push them into Joplin all on the same device.
Supernote is also Android-based, but they lock the app installation down. But they also have very capable longhand-to-text recognition and have semi-streamlined processes for exporting that text off of the device.
The Boox devices try to be mini-laptops with slick handwriting features. The Supernote devices focus on your handwriting above everything else.
I find this developing e-ink device space very interesting.