Yeah, I was hoping for at least a programmatic method (eg using one of the links from the account to stepover) if not a numeric conversion.
I guess it might be possible to use product names but I dount that will help with unlisted items in any case so it's unlikely to be worth the trouble.
It's so weird that GOG keeps information about which files associated with a game are patch files / lanaguage packs /etc and the Galaxy API download links on the product page but not on the account game details page.
There must be some kind of link (the server had to know which games to add to your library somehow) but it's obviously not publicly accessible.
Some games (like those that come in packs) don't even share a name so it's not a perfect solution by any means.
Yeah, it's very frustrating when the information you want is their just not in a way you can use it...