When using the AMP for Email form component, is it possible to redirect the user to a web page when one clicks the form submit button within the email?
No, it's not allowed. There's a section on this for the AMP for Website format: https://amp.dev/documentation/components/amp-form/#redirecting-after-a-submission, but notice that the section is not there for the email format: https://amp.dev/documentation/components/amp-form/?format=email.
See also https://github.com/ampproject/wg-amp4email/issues/17#issuecomment-1192025183.