This type of product exists. Epson produces (somewhat expensive) “EcoTank” printers that accept bulk ink poured into reservoirs. Epson has always been the odd-one-out for using piezoelectric print heads, which are separate from the ink cartridges and rarely replaced. I suspect this made it easier for them to implement a bulk ink reservoir system. Other brands tend to use thermal heads that are part of the ink cartridge. (IIRC, Canon is the other odd-one-out for using thermal heads that are separate from the ink cartridges).
Perhaps it’s possible to design a printer around replacement print heads meant for Epson printers. Alternatively, a partnership between Purism and Epson would make more sense than a partnership between Purism and another brand that has a razor and blades business model to defend.
Laser printers are great. There’s no ink to dry out, the print quality is consistently high and water resistant, and only HP’s PageWide inkjets can compete with them on print speed. But I imagine it’s easier to develop an inkjet printer. I also tend to think of all those plastic toner particles dispersing into the environment, but on the other hand it’s not clear to me as a layperson whether inorganic inkjet inks are any better.