Thanks for tagging me but i think @DanielGirardBolduc has made the list and has the best knowledge of different topps variants, i can also help with the basic variants between different sets and languages and smaller differences i’ve learnt from him but contacting him probably gives the most certain and up to date knowledge 
here’s also A list of variants he has posted here, mostly about topps series 1 variants but also info about series 2 where gengar is included
Also here’s the Cameo thread , it should have one more cameo that isn’t on Quuador’s list but it only has the english cameos so for example the natta wake one isn’t included
And when it comes to non-tcg as whole, that unfortunately is a wild west with only bits and pieces of information here and there, there’s several threads here of certain card brands and sets but This thread might be a place where you can get the most ideas what might exist. Anyway sounds like a very cool collecting journey and i hope you’ll share here what you’ve already managed to get and new arrivals when you acquire them