Is the function already live? I couldn't find it...

You need to use crust.piefed.social and it works on Lemmy comms.

You need any type of review and scoring mechanism to show the source of reviews.

I took a look at the link and I'm not sure how to use it, it looks like the instances don't really get reviews, but instead get endorsements that function like upvotes?

I also didn't see any way to look up the instance you wanna learn more about community sentiment on. I'm not sure if that site quite fufills my needs

Some of them deserve it.

Perhaps ratings could only be counted by accounts not currently banned?

But will the community ratings be public?

Noob question:
Is piefed and lemmy two different projects?

Yep. Two different platforms with different developers

Ehhh that one I could do without

but they are interoperable (as you see, the above 2 folk are on lemmy, and I am on piefed).

Instances can endorse or blacklist other instances, and there's a web of trust system implemented, though I'm not sure of the exact details.

Oh no not the mods

Yes. And must be a member of the community for a while. Not sure how long yet. It's currently 1 day but will probably change it to 1 week?

At minimum, but if the delay were a month that would probably still be fine.