Sidecar: Mirror Display

How

1. On the Mac, open Control Center
2. Click Screen Mirroring
3. Choose your iPad
4. Open System Settings → Displays
5. Set the iPad to mirror the Mac display

Try this

Mirror your Mac to the iPad, then move the pointer on the Mac. Confirm the iPad shows the same screen in real time.

Why it works

Mirror your Mac screen onto the iPad.

Same Mac screen, two places.