USB Magic keyboard not recognized by new Mac Mini M1.

Hello sabMACuser,

Let's start off by checking the helpful steps in this article that was linked to your posting which can help with this issue: If you can't connect your Magic Keyboard, Magic Mouse, or Magic Trackpad to your Mac - Apple Support. Follow this guidance:

"Turn the device off and on

Magic Mouse has a switch on the bottom of the device, and Magic Keyboard and Magic Trackpad have a switch on the back edge of the device. Slide the switch to turn off the device (no green is visible), then slide the switch back to turn on the device (green becomes visible).

Earlier Apple Wireless Keyboard and Magic Trackpad models have a power button on the right side of the device. Hold the button until the green LED on the top of the device turns off, then press the button again until you see the green LED to turn the device on.

Make sure Bluetooth is turned on

Using your Mac notebook's built-in trackpad or a USB mouse, choose Apple menu  > System Preferences, then click Bluetooth. Make sure that Bluetooth is turned on.

If the Bluetooth icon doesn't appear, or if the menu bar status continues to indicate that Bluetooth is off, restart your computer and then try to turn Bluetooth on again.

Connect the Lightning cable

Connect your wireless accessory to your Mac with the Lightning to USB Cable or USB-C to Lightning Cable, wait 1 minute, then disconnect the cable. This pairs the accessory with your Mac and charges the built-in battery. To check your accessory's charge level, click the Control Center icon  in the menu bar, then click Bluetooth.

Earlier models don’t use a Lightning cable for charging, but have batteries that you replace. Learn how to pair those devices with your Mac.

Check for wireless interference

If your accessory won't stay connected wirelessly, there might be interference with other wireless devices. Learn how to resolve Wi-Fi and Bluetooth issues caused by wireless interference."

Let us know if we can help with anything else at all or if this doesn't settle your issue so we can look into this further with you. Thanks and have a fabulous day!