Help with 2019 27" iMac i9 upgrade path?

[dcpmark]

I purposely bought this model as the last one that could boot Mohave for the 32bit apps I still need access to. I mistakenly thought I could always buy another desktop in the future and use my iMac as a monitor, thus retaining the ability to run Mohave whenever I needed to. I now know that this is not possible absent a questionable software solution, but I want to pick up a new Mac Mini M4 for my daily use. I don't want or have room for 2 monitors, so what are my options? Seems like getting rid of the iMac, and getting the Mac Mini M4 and a 2018 Mac Mini i7 to run the old stuff when I need to is the only way I can see. I can connect both Minis to one 27" monitor, right? Any other options?

TIA, and please correct any wrong info I have.

 

[Abazigal]

I purposely bought this model as the last one that could boot Mohave for the 32bit apps I still need access to. I mistakenly thought I could always buy another desktop in the future and use my iMac as a monitor, thus retaining the ability to run Mohave whenever I needed to. I now know that this is not possible absent a questionable software solution, but I want to pick up a new Mac Mini M4 for my daily use. I don't want or have room for 2 monitors, so what are my options? Seems like getting rid of the iMac, and getting the Mac Mini M4 and a 2018 Mac Mini i7 to run the old stuff when I need to is the only way I can see. I can connect both Minis to one 27" monitor, right? Any other options?

TIA, and please correct any wrong info I have.

It looks like it could work. I wonder if you could also keep the Intel Mac mini powered on as a "headless" Mac, and then remote in to it via your M4 Mac Mini, allowing you to effectively run 2 versions of macOS without having to keep switching between the two.

 

[dcpmark]

It looks like it could work. I wonder if you could also keep the Intel Mac mini powered on as a "headless" Mac, and then remote in to it via your M4 Mac Mini, allowing you to effectively run 2 versions of macOS without having to keep switching between the two.

I’m going to use the Intel Mac so infrequently that I don’t mind switching when I need to access the older system. Of course, I just wish I could add the M4 Mac mini to my current setup, and keep using the beautiful 27” screen of the iMac.

 

[Fishrrman]

If you get a third party (non Apple) display with multiple inputs (such as HDMI + USBc), you might be able to have two Macs connected and switch the display's input source.

But then, what about keyboards and mice?

Maybe one of those "KVM switch" gadgets is what's needed here (don't know much about them, never used one).

 

[Nguyen Duc Hieu]

If you get a third party (non Apple) display with multiple inputs (such as HDMI + USBc), you might be able to have two Macs connected and switch the display's input source.

But then, what about keyboards and mice?

Maybe one of those "KVM switch" gadgets is what's needed here (don't know much about them, never used one).

With some model of bluetooth keyboards and mouses, user can switch control among 3 devices with hot key combination.

 

[Chancha]

It is pretty common for modern mid to high tier monitors to already have built in USB KVM, especially for those that have type-C input.

Also even without it, as mentioned by others above, remote accessing the Intel mini from the M4 mini is pretty trivial once you set it up. I reckon for infrequent use this may be more ideal than thinking about KVM / monitor sharing.

BTW, there are people who have tried to modify the iMac 5k into a 5k display that accepts inputs from other sources, it involved putting in an LG board that was supposed to go into their standalone 5k displays. To me this has always been a future route for my aging 2017 5k iMac, but not until the Mac part of it is broken or severely outdated (it is not, yet).

 

[PaulD-UK]

"...there are people who have tried to modify the iMac 5k into a 5k display that accepts inputs from other sources, it involved putting in an LG board that was supposed to go into their standalone 5k displays."

Not a LG monitor control board but a replacement video control board sourced from China.
This makes an excellent, DP/HDMI/USB-C multi-input, display, visually as good as the iMac.
The thread about this is here:

 

[Chancha]

"...there are people who have tried to modify the iMac 5k into a 5k display that accepts inputs from other sources, it involved putting in an LG board that was supposed to go into their standalone 5k displays."

Not a LG monitor control board but a replacement video control board sourced from China.
This makes an excellent, DP/HDMI/USB-C multi-input, display, visually as good as the iMac.
The thread about this is here:

Wow thanks, I need to bookmark that thread. Been hearing bits and pieces of how that works, didn't know there is such a long running discussion.