After messing with the Python script, I started to dump the whole thing. As a first try, I did dump a few kilobytes of data. Using that YY-CHR app (https://w.atwiki.jp/yychr/),  I'm seeing something - there are sprites, cut-outs and whatever that looks very familiar. However, they look pretty distorted and this one looks like letters and numbers in 8x8 fonts but they look mashed up pretty badly:

 After changing how it dumps the code (the endian-ness) I can see something more clear here now:

As this code is not really polished and experimental, I'll be putting up the code and schematics on Github once I get the proper full dump. Next thing is, try to dump the entire thing and possibly run it with the modified Nintendulator which works on the VT-03 ones.

Good thing is at least the ROM carrier board is based on the one that is shown earlier (link: https://www.eevblog.com/forum/beginners/fun-project-hack-cheap-handheld-console-help-with-bga-nand-flash-chip-needed/):