Third-party service, then
Third-party service, then
Would have to be off network. I think it's important that folks know how their data is visible, so take a look here to see your repo... atproto-browser.vercel.app/at/emmeline....
Bsky is focused on decentralization over privacy. That decentralization gave us blacksky and the work happening there, but it's possible because everything short of DMs are on the public firehose.