Does anyone know if AppleCare will cover the keyboard if I buy the iPad and keyboard from Amazon?

Yes.

Input devices tied to the covered iPad are also covered, though any incident is considered separate to the iPad if both are damaged. So you would use up 2 incidents of accidental damage.

https://www.apple.com/legal/sales-support/applecare/applecareplus/2410/241015_applecareplus_uk_tc.pdf

Assuming of course that the keyboard is made by Apple. A third-party keyboard would obviously not be covered by Apple's warranty or under AppleCare+.

Regards.