Is it possible to use screen sharing without the remote screen being visible?
There are three solutions that I know of that allow you to "black out" the remote screen so that uses cannot see what you are doing:


Apple Remote Desktop (ARD).  Cost:  $79
TightVNC.  Cost:  Free for personal use.
TeamViewer.  Cost:  Free for personal use ($810 for Business License)


As for ARD and VNC, they will do they job, but as far as performance, they are quite frankly, horrible.  ARD is definitely better than VNC, but if you are comparing it to Microsoft Remote Desktop, then ARD looks and feels prehistoric.  The VNC protocol is quite "heavy" and the lag on a LAN is unbearable at times.  But, for the price...

I wholeheartedly recommend TeamViewer

TeamViewer, is one of the best remote access / remote control utilities out there.  It's free for personal use but to buy a license it's expensive.  If you have many clients to manage, TeamViewer is the one.  There is zero setup involved. unlike VNC which you have to open ports on your router.


TeamViewer does have the capability to black out your screen and you get this feature with the free version - you don't need the paid version.  I tested this today and it works.  To do this, you have to first disable remote input, then click on show black screen.

Below are the screen captures of my TeamViewer session from my iMac to a Dell Laptop running Win10 with the black out option enabled:



If you notice the black screen on the laptop below.  All you can see is the pointer arrow and that moves with the TeamViewer session and not the remote mouse/keyboard.