It would be nice to set up these Silos in Matrix identity servers so that you can find your friends. This currently works with email and phone but adding facebook, instagram, snapshat, twitter... would be a nice step forward.

No, because you can't disable Facebook Messenger if you have a Facebook account, and people will still message you there.

The Facebook accounts must be deleted as part of any solution.

Alternatively set your status to "email me" and just never go to facebook again.

That worked for me but that was 5 years ago.

I guess it's google accounts then. No one uses their messengers because they keep changing names.