I am working on a web app where this is one of the features i want to have, but the biggest issue i'm facing is that the same post from different instances have different id, and I am not sure if there is a way to get the id of a post in a different instance... If anyone has an idea of how to do this I'd love to know!

The one without the @ part should be the community from your instance (e.g. if your account is in lemmy.ml then it is android@lemmy.ml). Since it is local, they just do not display the @ part

Hi, I migrated from MAL to Anilist a few years ago, I'm pretty certain it does import from MAL