The goal of XPipe is to be connection hub that brings together your tools, not really replace them. For example with RDP and remmina, XPipe has an integration for remmina to launch RDP connections directly, making it easier for you to quickly boot into RDP sessions. Especially when you combine it with the automatic SSH tunneling functionality for RDP that is also included.
For VNC, as the a landscape of tools to integrate is a little bit less populated compared to RDP, XPipe has a built-in VNC client. However, if you still want to use your own VNC client, you can do so using the service tunnel functionality.
Very nice then. I looked through the page and did not saw anywhere mention of any remote desktop technology, but I also did not looked thorough enough.
