1. A method of customizing a user equipment (UE), comprising: receiving by the UE a definition of a group identity (GID) of the UE that comprises a UE model identity and a wireless communication service brand identity; receiving by the UE a customization manifest, where the customization manifest identifies a plurality of feature customization policies and a plurality of user feature customization override policies, where each feature customization policy defines which of a predefined number of feature customizations are to be active for a UE, and each user feature customization override policy defines which of the predefined number of feature customizations are to mandatorily be applied notwithstanding preexisting user customizations of the associated feature, whereby the customization manifest defines different feature customization policies to be applied to different UE models and for different wireless communication service brand identities and one of overrides or permits retaining preexisting user customizations of features; searching in the customization manifest by a customization client application executing on the UE using the GID of the UE as a search key, where the customization client application is triggered to execute by one of a UE activation process, a UE rebranding process, or a UE change of service provider; finding and selecting a feature customization policy in the customization manifest that matches the GID of the UE by the customization client application; reading the selected feature customization policy from the customization manifest by the customization client application; finding and selecting a user feature customization override policy from the customization manifest that matches the GID of the UE by the customization client application; reading the selected user feature customization override policy from the customization manifest by the customization client application; identifying preexisting user feature customizations on the UE by the customization client application; and based on reading the selected feature customization policy, based on reading the selected user feature customization override policy, and based on identifying preexisting user feature customizations on the UE, customizing one or more features of the UE by the customization client application and not customizing one or more features of the UE that is identified for customization in the selected feature customization policy for which a preexisting user customization is identified and for which the selected user feature customization override policy allows retaining a preexisting user customization, where the customizing takes place as part of one of a UE activation process, a UE rebranding process, or a UE change of service provider.