How to run Sierra on 2019 iMac

[golfgirlgolf]

There are a couple of old programs not supported on Mojave which I would like to be able to occasionally access via bootable backups I have around.

Surprise - (not really) - my new 2019 won't boot on one of those backups. I get the circle-backslash symbol.

Simple answer - buy a little spare Mac Mini for these tasks -

But, is there any way to make my 2019 iMac go retro?

Bootable partition that's an emulation - virtual machine? (similar to running Windoze)

Any other approach? SDK?

 

[redheeler]

You can run older versions of MacOS in a virtual machine. Only downside is the performance will suffer due to lack of graphics acceleration, how much this matters depends on the apps you're trying to run.

 

[Fishrrman]

You can't BOOT a 2019 iMac using Low Sierra (or High Sierra either).

You CAN run those OS's in a "virtual machine", as mentioned above.