There are some solutions, such as Duet Display: https://www.duetdisplay.com/blog/how-to-use-your-imac-as-a-monitor https://www.duetdisplay.com/blog/how-to-use-

There are some solutions, such as Duet Display: https://www.duetdisplay.com/blog/how-to-use-your-imac-as-a-monitor https://www.duetdisplay.com/blog/how-to-use-your-imac-as-a-m... Apparently you can use a TB cable to connect it up, so it might be reasonably performant as a productivity monitor! I think you can also extend to some displays using AirPlay, but from memory performance wasn’t great when I tried.