If you want to turn an Android tablet into a second screen, or want to use a Windows PC with an iPad, Splashtop Wired XDisplay will do the job for $10 (you can try it for free first).

Sidecar in macOS turns your iPad into a second display, but it's limited to certain Macs and iPads. Thankfully, a few ...

How to use an iPad as a second screen for Windows Windows can’t use your iPad as an extra display out-of-the-box, but there are a few third-party apps you can use as a workaround.

How to Use spacedesk to Mirror or Extend Your PC’s Screen Onto an Android Tablet Before you can mirror or extend your Windows PC’s screen to your Android tablet, you need two things.

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 ...

Duet Display lets you use any Android device as a second screen for your Mac, whether wired or wireless, giving you extra space for multitasking.

This guide takes you through the steps to set up and use an Android device as a second screen for Mac using wired or wireless methods.

For example, you can use your iPad as a second screen for your Mac with minimal effort, and there's no need to fiddle with annoying cables and questionable software hacks.