I just remembered ntfy's server-sent events implementation, mistook it for websockets, and thought, man, that could be useful for server-executed TUIs and interactive CLIs!
Turns out, cURL has Websockets support but not in the CLI. It's planned to eventually, and when it does, I kinda hope there's an option that sends a few CLI/TUI-related convenience headers when starting the socket, so one could run i.e. curl wss://calckey.foo/curl --tui-headers and get a full blown network-oriented TUI!