Lately I've been working on a little side project: https://codeberg.org/silverpill/activity-connect

ActivityConnect a simple AP-to-AP bridge, similar to activitypub-proxy. It's not quite ready for production yet, and only works in read-only mode.

The primary goal of this project is connecting Tor and I2P instances with clearnet instances, and it will be also useful for circumventing instance blocks.
Connecting DID-based actors with domain-based actors is in scope too, but I don't know yet if that will be necessary.