There IS a trick, but myself won't danger my comp for that feature.
Got to /System/Library/PrivateFrameworks/SidecarCore.framework/Versions/A/SidecarCore and copy a SidecarCore file for backup.
Then you have to boot to recovery mode (cmd+R) then open Terminal and input csrutil disable and reboot to standard mode.
Then dowload a patch from this link: https://drive.google.com/file/d/1G0sJa7vr6G9qFwsXIBvW06lhq3g3_EQN/view?usp=sharing
Open Terminal and input chmode drop patch onto Terminal and press Enter. Then write sudo and drop the file again and press Enter.
Reboot, Open System Preferences and here you go.
Notice that image quality is bad and slow. Also wired connection only. So it is no marketing that Apple restricted support on old models.