If the space is available on the remote machine, I’d probably backup into a local repository on the remote machine, and use rsync (with --delete, so that files removed remotely are deleted locally). This solution has the most redundancy.
Another solution is to run the REST server on the local machine, use ssh with a remote port forward (e.g. run the REST server on port 8000, then use ssh -R 8000:localhost:8000) to forward the REST server port to the remote machine. You can then run restic with the REST backend on the remote machine to connect through the SSH port forward to the REST server on the local machine. I’ve heard that this works very well for several users.
If you do this, please make sure to configure proper authentication for the REST server, otherwise all processes on the remote server can delete data in the repo!