Last time I tried krdp, it didn't fit my needs. I needed to have already started krdp locally if I want to connect remotely. Neither x11vnc nor freerdp-shadow have that limitation.
It is possible to start it on-demand via the command-line. That is how krdp is developed and tested. You will need to pre-authorize krdp to the portal system, though.
If you can shell in, I don't see why not? It's a command-line thing. It's intended to also be usable for things like Ansible. If it doesn't work, please file bug reports!
