The Monon Color is another obscure handheld, which never got released in Europe and America...
I got contacted, if i can make a Flashcart for this system and got shipped a complete console and two games afterwards.
So here's the first Flashcart for this system. It can hold any games from 4mb to 16mb and the cartridge has a nice 3D-printed case.
You will need a programmer, which can program 25Q128 chips (e.g. the TL866II Plus is most likely the cheapest option, if you don't already have a programmer).
Also included is the "Program-Adapter", which can get used to program the Flashcarts and can even get used for dumping original cartridges.