At one point people were speculating about monitors with eGPUs built in. What would be super cool is if Apple could take this further and you could use an iMac

At one point people were speculating about monitors with eGPUs built in. What would be super cool is if Apple could take this further and you could use an iMac as both a second screen and off load work to the CPU and GPU. I'd like that from an eWaste perspective if nothing else. i.e. just add a new iMac to your existing set up. For myself I've been using the same external 27" Dell 1440 monitor for about 7 years. It's not like it's worn out in anyway.