If you have an old Android tablet lying around that you're not sure what to do with, why not use it as a second display for ...

spacedesk is a free program that turns an Android tablet into a portable display for your Windows PC that you can easily carry with you anywhere. You can use it when you need extra screen space or ...

I literally have no idea how using your S9 Ultra as a 2nd monitor works, you mention both wired and wirelessly which doesn't help clarify at all. Could I ask you to explain that to us? But at a lower ...