iPad to external monitor connection problem

I am trying to run a Powerpoint presentation on my iPad Pro 2024 (11") running IOS 18.0.1 and display the output on an external monitor. As a practice, I am using my Mac Studio desktop with Studio Display as the test.

I can connect the two devices either by cable or wirelessly, but in either case I can only get the desktop screen to show up on my iPad, not the other way around. I have tried rearranging the screens in the display settings dialog on the desktop, but it doesn't make any difference.

On the iPad, I never see the Studio display as an option under the Displays settings. I have tried unplugging the USB-C cord that connects the PC to the monitor and using that with the iPad but still no joy.

FWIW, I have also discovered a quirk that matters only to anyone using the Dvorak keyboard layout: when you want to arrange the displays in the desktop settings the option key doesn't work while Dvorak is active. You have to switch to the regular US keyboard.

Any help would be greatly appreciated.