is there an option to use Face ID on an iMac M4 ?

Face ID works on iPhones and iPads thanks to their TrueDepth camera system, comprised of high quality cameras and a dot projector, which projects the 30,000 dots needed to identify your face.

You can read more about Face ID here: About Face ID advanced technology - Apple Support

TrueDepth is not currently available on Macs. If you need to quickly unlock your Mac without having to input a password, you can pair an Apple Watch and enable this functionality in System Settings under "Login Password"

Nope!

If you have an Apple Silicon Mac, you can get an Apple keyboard that has a Touch ID sensor.

Your welcome and you can always provide feedback to Apple at Apple.com/feedback

They will read it however do NOT expect a reply.