I also had a disk for Oki (don't know if same model) with the Microsoft Stand-Alone BASIC, instead of CP/M.
On Mon, 15 Nov 2021, pleasefixthisbrick via cctech wrote:
Unfortunately, the model 20 was a different architecture all together. I have begun looking into Japanese museums. Maybe there is more documentation and data in its country of origin.
I don't know where Okidata's primary markets were, but, the sample disk that I had came from Russia!