I have the iPad Pro (12.9" 3rd Generation) running iPadOS 15, and an Intel Mac Mini running MacOS Monterey 12.3.1 (latest versions per of this writing).
The iPad Pro is connected as Extended Display, which shows a MacOS Desktop space on the iPad.
I currently have the Apple Pencil (2nd generation) and the iPad Pro Smart Keyboard Folio (without Trackpad). Both of these devices can control the MacOS computer. The Keyboard be used to type, and the Apple Pencil can control the mouse cursor in MacOS. (NB: Unfortunately, touching the iPad screen via fingers does not control the MacOS mouse cursor).
Can the iPad Magic Keyboard (with Trackpad) steer the cursor when iPad is an Extended Display for MacOS like this? I simply want to be able to control the mouse cursor on my Mac with the iPad's Magic Keyboard Trackpad.