I was aware of Canon's mid-90s attempt at the same thing: Canon IS-32 Color Image Scanner Cartridge.

While the Canon may be the first color-capable unit, it's interesting to see it wasn't the first ever!

I vaguely remember that AppleWriter on the Apple IIe exposed the escape sequence it used for character-mode print commands like bold and underline to the user. You could change the command to escape sequence maps right from inside the program. I re-mapped bold to cyan, and underline to magenta just to see magic color come from that printer. That one day in 1996 was probably the only time that printer ever printed in color, and probably my first time to see a printer print in color.