As you said yourself imaging is dead, or at lest not supported by apple anymore. But there is software like Acronis True Image which still allows you to make a complete image and restore it to the same or another mac. I’ve tried this with Mac Minis 2018 (T2) and it worked but you loose MDM enrollment in the process. That’s why it isn’t an option for us, might be different for you.
With MDS you can install various software as pkg by including them in your workflow. Custom user settings like wallpapers can be set through a postinstall script (there are already some predefined ones in MDS like changing to dark mode) or with custom mobile configs. To achieve everything we needed, I had to rely on a combination of scripts and custom profiles.
Of course you would have to create a different workflow for every computer/user if they are all different which is probably not very efficient.
Hope this helps to clear things out!