As stated in https://docs.microsoft.com/en-us/power-platform/important-changes-coming#some-client-apis-are-deprecated Xrm.Page is deprecated and the replacement in terms of forms is the formContext which can only be obtained using executioncontext.getFormContext()

However the executionContext of the Dynamics 365 form is not made available to widgets added to CIF v1.0 or I believe v2.0.