correct. You still need a client. The Op is probably referring to getting around firewall restrictions. Some companies block all outbound ports except p80 and p443, so if you work at such a company, you can't access your personal machine over p22. Shellvault lets you do that on p443. But so does changing your SSH server to listen on p443.

A self hosted version of this might make a little more sense. However, it is still putting all your credentials in one place.

I mean there is also Teleport (Gravitational) that you could self host and get around most of those issues.