2021 M1 iMac 24 inch.
…can it be 1 of my 2 monitor setup using a new M4 Mac mini?
No it cannot. If you want or need a 2nd display for the new M4 based MM you need to buy one. Please remember iMacs are computers, they are NOT external displays for other devices!!!
No it cannot. If you want or need a 2nd display for the new M4 based MM you need to buy one. Please remember iMacs are computers, they are NOT external displays for other devices!!!
The iMac cannot be used as a monitor for any of the newest Macs and Target Display mode is no longer a feature of macOS, having been deprecated years ago.
Please see: Use your iMac as a display with target display mode - Apple Support
Per the link above:
• Your target iMac (monitor) must be using macOS High Sierra 10.13.6 or earlier.
• In all cases the source Mac that you're connecting FROM must have been introduced in 2019 or earlier and have macOS 10.15 Catalina or earlier installed.
You might consider a third-party solution - Luna Display or Duet Display - though the performance of those options is limited and really not suitable for motion images. Regardless, you still will need a proper monitor to set up either of those options.
Do yourself a favor, avoid the headache and just budget an extra $100 for a monitor. Yes, they are that inexpensive.
iMac as display for new M4 Mac mini.
