Using second iMac as monitor - can I still access its drive? | MacRumors Forums
Apple's 27-inch iMac converted into a cheaper Apple Studio Display with a 5K resolution and a built-in webcam - NotebookCheck.net News
You Cannot Use the 24-inch iMac as a Target Display (External Monitor)
How to Use a 27″ iMac as an External Display for Another Mac | OSXDaily
Incase anyone ever needs the answer…I have a 27” 2010 iMac working in Target Display Mode with a M1 MacBook Pro using a miniDP to USB C adaptor that's capable of 4k60Hz.