I would be great with a browser extension that could complement this site with functions that aren't otherwise possible like:
- Epic library import
- store.steampowered.com integration
- library import for other stores, like Amazon games
I've read that the reason you can't import other stores than Steam and GOG are that they don't provide an API for it. So a suggestions could be to create a browser extension (or separate application/script) that can fetch the users games locally on the users machines and then upload it to your server.
If you went the application route you could use Legendary to get the users Epic games, use one of the methods to login, and then run
legendary list to get a list of the users games. Similarly you could use nile to get Amazon games.