[ChildOfChaos]

I am in the same boat as I have an iMac 2015, although I specced it up from Apple at the time and it's just about holding on.

You can buy something like the camlink 4k from elgato which will give it a HDMI via video capture. I'm actually typing this now on a windows laptop that is connected to this.

It just means you need to boot the Mac and run the app, put it full screen and then you are done. The fans go like crazy though and obviously you need a working Mac.

I love this machine, but when it's time to upgrade, i'm going back to a seperate monitor setup for this reason. Maybe a studio display + mini.