While recovering from cancer treatments and moving, I heavily cut down on spending money for my IT infrastructure as you can only spend money once.
Now that I have recovered quite a bit, and also gaining more income, I got more recent Apple hardware and could start to use this: [Wayback/Archive] Use an iPad as a second display for a Mac – Apple Support
It’s called Sidecar in Apple terminology and actually quite neat, though you need extra software to use the iPad in portrait mode (it is hard coded to landscape though a 10-inch iPad Pro fits very nicely in portrait position next to a 16-inch M1 MacBook Pro).
If I persist, I need to look at solutions like [Wayback/Archive] Rotated Sidecar · waydabber/BetterDisplay Wiki · GitHub ([Wayback/Archive] GitHub – waydabber/BetterDisplay: Unlock your displays on your Mac! Flexible HiDPI scaling, XDR/HDR extra brightness, virtual screens, DDC control, extra dimming, PIP/streaming, EDID override and lots more!)
Sidecar is part of Handoff, so these preconditions apply: [Wayback/Archive] Use Handoff to continue tasks on your other devices – Apple Support.
In the end, I think it is all based on AirDrop, especially because of the first Apple Support link above mentioning these “Additional requirements”:
Both devices must be signed in with the same Apple Account using two-factor authentication.
To use Sidecar wirelessly, both devices must be within 10 meters (30 feet) of each other and have Bluetooth, Wi-Fi, and Handoff turned on. Your iPad must not be sharing its cellular connection and your Mac must not be sharing its internet connection.
To use Sidecar over USB, your iPad must be set to trust your Mac.
Via:
The Wiert Corner - irregular stream of stuff 