The dump does seem awfully small for the given number of games, even when accounting for repeated titles. I could not find any writes anywhere in the entire ROM image to important VTxx registers $4100 or $410B, so my assessment is that the menu is just missing. I also could not find the CHR data of some of the games depicted in the various YouTube video describing this handheld.
I find the "variant of the VT series where the reset vector is entirely different" explanation extremely unlikely. The only VT series chip that allows such a thing and that is still NES-compatible is the VT369, which allows the reset vector to be stored inside a 4 KiB ROM that is embedded in the NOAC chip itself. In every known instance, that 4 KiB ROM only contained code to download and execute LCD initialization code from an external serial EPROM, and the other 2 KiB half containing code for the sound CPU. Even if one allowed for a super-special embedded ROM variant, it would not fit an entire menu.