If you're gonna go through all of this work -- including creating and maintaining private keys -- why not just restrict the SSH server to only permit key-based

If you're gonna go through all of this work -- including creating and maintaining private keys -- why not just restrict the SSH server to only permit key-based authentication (optionally, signed by your CA)? If having 22/TCP open to the world is an issue, then set up Wireguard on the host and only allow SSH connections that are coming in over the Wireguard interface. Got a bunch of machines to deal with? Set up a jumpbox or two running OpenBSD, lock it down, give your users access to it via SSH (optionally, over a Wireguard connection) and then only allow SSH access to all of those other hosts from the jumpbox(es). Then there's the fact that I have a whole lot more trust in the security of OpenSSH than I do some random web application! To me, this just seems kinda pointless -- there's a bunch of other, better (IMO) ways to deal with this -- but I guess if it fits your needs ...