Doesn't seem very fast, but I really want this for our hackerspace. Speaking as the guy who has to print out all the meeting minutes.

The only way it could be better is if they somehow made it run on ballpoint pen ink.

That's just a pen plotter. https://terrapen.xyz/

Not the same thing at all.

I wonder if the pen could also be at an angle. You know, because calligraphy.

I vaguely understand, like plotters are for vectors (design, architecture) and inkjet printers are for raster images (photos, receipts). What other key differences are there?

That's the difference. Printing out an A4 document full of type would take forever on a plotter and not look particularly good.