Magic Mouse 2 compatibility with my IMac

According to the Technical Specifications of the Magic Mouse 2, it should also work on your macOS:

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System Requirements

• Bluetooth-enabled Mac computer with OS X v10.11 or later

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copied from: Technical Specifications Magic Mouse 2

It works fine on iMac Late 2012 with Catalina and should work on all Macs. Just follow the specific instruction for Unpairing any previous Apple Mouse and pairing the Magic Mouse 2 as new. Required setting up the Magic Mouse as new with the First setup with Lighting to USB Cable supplied in the box.