Does anyone know if there is a way to run a photon application from a telnet session?
Well you can start it but it will be displayed on the running photon session.
In a sense that is what Phindows does. Not using telnet, but over the network. An actual telnet session has no graphics capability.
example how to run detached photon app
# ls /dev/ph*
# PHOTON=/dev/photon /bin/on -d /usr/photon/bin/pterm/dev/photon is physical photon console, /dev/ph are virtual photon consoles (e.g.: phindows)