We assume that you are talking about spacedesk Viewer for Windows.
We are aware of the described (Ultra)VNC approach.
We will implement this feature as soon as a corporate customer will pay for it.
This is not expected to happen any time soon.
In the meantime you could use the “Mouse as Touch” setting.
This uses the local mouse to raise touch events.
It is actually very close to the feature which you are requesting.
Please let us know how this works for you.
