on the manufacturer’s website it is indicated that the memory card should only use the one offered by the manufacturer
You can use any microSD card.
There is an English-language review, where a man shows how to create locations in the root of a Rome memory card and throws games into it using some kind of program.
As for the review, I will not say anything, but in the videos that I dropped, in the instructions for flashing, the dude using the program (as the CD burned in its time, the popular nero burning rom, daemon tools, etc.) records the image on microSD. In this image, there is already a custom firmware and in the future the device is just loaded from it. After recording this image, all these directories, including rom, already exist, you do not need to create anything.