A miyoogamelist.xml allows you to add clean and correct names to your roms when browsing in Onion. It can be used with all main console systems on Onion but is of most benefit where renaming the rom file itself is not an option, i.e. for Arcade based systems (ARCADE/NEOGEO/CPS1/CPS2/CPS3) where doing so would break the rom and prevent it from working.
There is not yet a known way to use miyoogamelist with sub folders (it will display on the device only as a single list/folder even if you scraped/generated a list from subfolders)
My comments
Love the idea of better names.
Do not like the idea of losing subfolder support.
Need to test.
I can confirm subfolders do not work. So do not use.