"Proxy jump

"It is often the case that some SSH hosts can only be accessed through a gateway. SSH3 allows you to perform a Proxy Jump similarly to what is proposed by OpenSSH. You can connect from A to C using B as a gateway/proxy. B and C must both be running a valid SSH3 server. This works by establishing UDP port forwarding on B to forward QUIC packets from A to C. The connection from A to C is therefore fully end-to-end and B cannot decrypt or alter the SSH3 traffic between A and C."

More or less, maybe but not automatically like you suggest, I think. I don't see why you couldn't configure a generic proxy to set it up, though.