One possible lead I forgot to mention.
"T&T Technology Corp" is a name that keeps popping up, either engraved onto the back of cartridges or as
some sort of sticker, and I've seen it once or twice on consoles too. Unfortunately I can't make much headway on it because the name "T&T" is super common across all sorts of industries, although I can't imagine it's still trading under that name today.