I have a feeling there are two platforms going on, which are confusing things. There is this platform, which is probably some random microcontroller, and there is the NES based platform that I have also now dumped (the 300 in 1) which use some kind of new NOAC with similarities to the VTxx architecture.
As far as I can tell there is nothing in common between these platforms except a low resolution screen - and a broadly similar CPU architecture, although the non-NES based ones use a 65C02 or similar enhanced variant whereas the NES ones use a plain 6502.