A few other comments have concentrated on the printer head and ink cartridge, but the roll vs sheets interests me. Manipulating sheets of paper is actually quite a difficult problem to solve - and there is only a demonstration of paper placement. Loading page after page is actually really not easy at all. There is no example of it printing.
I see they got a nomination for a design award [1], which in my personal experience has been a negative signal for successful projects. On the same page they mention that they also mention that they don't even know how much this will cost yet:
> We know this is your most frequently asked question! Final pricing depends on a moving puzzle of production volumes, BoM costs, industrialization expenses, regulatory certifications, and final engineering developments.
On the crowd funding page it mentions for parts [2]:
> Main board: Raspberry Pi Zero W
> Cartridge board: STM32 MCU
Not a specific MCU variant, and the specifics of the Pi variant (i.e. RAM) are not mentioned. I would expect these parts would be locked in by now. I have a feeling that this is not quite as ready as made out - I think there is still R&D going on.
[1] https://www.crowdsupply.com/open-tools/open-printer/updates/...