Yes and no,no because if u adding rating then someshow should be moderation of rating cause any random competitor app create a lot fake account and make fake downvotes to ur app and promote their own ,everything as in modern business done,so fdroid platform would need hire or put voluunter which would moderate it all and it heavy work

It's not in-store, but if an app is relatively mainstream it very well might have reviews on https://alternativeto.net/

There's Awesome F-Droid apps, which might be worth bookmarking.

https://fdroid.tabler.dev/

Totally agree. They could be the stars of their repository

There are ratings in Discover on Linux. I have absolutely no idea where they are pulled from but that might be the right platform.