@toddsundsted You can look up @minimitra, it is an actor hosted on my server and managed using the Mitra Mini client.

Its ID is a normal HTTP URI (compatible form). The first step is to convert this ID into canonical form ('ap' URI), so if this actor moves to another server, your software will be able to tell that it is dealing with the same actor. This trick also works with posts, activities, everything.

At the next difficulty level you can create portable actors. This shouldn't require major changes if you keep signing keys on the server. Not ideal, but okay for single-user instances.

Finally, there is client-side signing. This is really hard, and it is probably easier to develop a client from scratch than trying to adapt an existing codebase.