Is there like a master thread that collects the homebrewed species? If not is there interest in doing one? I'd love to have an easy access to that kind of information.

There’s the GMAC thread at https://community.fantasyflightgames.com/topic/128736-the-great-movie-alien-compendium

That probably has more information on this topic than anything else.

EDIT: Oh, and don’t forget the spreadsheet that I’m putting together for all the known official and unofficial races. See https://community.fantasyflightgames.com/topic/128736-the-great-movie-alien-compendium/page-7#entry1750775