Answering my own question, something that works is to pre-populate the /Library/Preferences/com.apple.keyboardtype.plist.

For example:

defaults write /Library/Preferences/com.apple.keyboardtype "keyboardtype" -dict-add "2050-1130-0" -int 43

(having obtained said values from a Mac where I had already used KSA to set up the keyboard).

THat's not exactly accurate.
Apple allows resellers to sell The Magic Keyboard which is Wireless, but it also connects with an Apple Lightning cable, which allows it to be wired or wireless. Granted, it's not the previous hardwired option, but it's still wired if you'd like it to be.
If your reseller is telling you otherwise, you might want to double check that.

The lack of a hardwired keyboard option (outside the iMac line, until that ends too) is NOT the same. It's a complete deal breaker for .edu and other deployments in which the input peripherals must be physically secured without modifying the hardware or the furniture.

Thanks to DanJ_LRSFC for posting this; we'll be "embracing" this new reality soon at my shop.

Appreciate it. I did a

defaults read /Library/Preferences/com.apple.keyboardtype "keyboardtype"

on one computer after configuring it and then created my script with the 'read' variables.

I was told that educational buyers still can get wired peripherals.

All thought, we sadly all ready use Dell keyboards and mouses for 2 or 3 years.

The standard black devices, since the apple mouses don't work on our desks and the apple keyboards loose their keys really fast.

I had to look into this recently as we use 3rd party Kanex wired keyboards for our iMacs and I found that while the above does work, the first user that logs into the iMac (after Automated Device Enrollment completes) will still be prompted with the keyboard setup assistant, even if you pre-populate the plist file talked about above. After that it doesn't pop up again after logout and logging in with the same and different accounts.

To stop it appearing alltogether I ended up adding the KeyboardSetupAssistant process to the Restricted Software section in Jamfs left main menu. This appears to be working with no KSA appearing for the first account that logs in.