Use iMac 27" in Target Display Mode with Raspberry Pi - Ask Different
Target Display mode is pretty Universal on the 27 inch iMacs from 2009 & 2010 with only a mini display port connection required. : r/mac
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.
How To Use an iMac as a Monitor for a PC
It's an environmental shame that “Target Display Mode” is not a thing anymore. : r/mac
The Ins and Outs of Your iMac's Target Display Mode
2016 Macbook does Target Display Mode on old iMacs (pic) | MacRumors Forums