Remote Desktop (Vinagre) is a remote desktop client application that I believe is included by default with Endless. Remmina is another remote desktop client that is available for Endless.
You should be able to locate these in the Software Center under the Utilities section.
Software for Endless is either included or available for install via flatpak. Generally all these applications should show up in the software center. I believe that the software from flatpak.org will automatically show up in the Software Center. Other applications that are distributed via flatpak can be generally be installed, but you will be on your own to locate the flatpaks. If you discover flatpaks not listed in the software center you can share them with the community by posting links in the forums.
bill