The transition toward software-defined vehicles requires standardization and modularization of hardware decoupled from software, along with centralized electrical/electronic architectures. While electrified drive units, such as integrated in-wheel drives, are expected to realize the hardware standardization and unprecedented flexibility in vehicle design, their implementation remains constrained by complex signal wiring between the module and the vehicle body and by control units decentralized across them. This paper proposes a modular drive architecture that achieves complete hardware-software separation by leveraging the power packet dispatching system. We introduce a sensorless control method that estimates motor internal states, specifically winding current and rotor angle, solely from physical quantities measured on the vehicle side. This completely eliminates the need for physical sensors in the drive module, reducing it to a passive actuator governed by the vehicle-side power system via a standardized packet protocol. The proposed architecture significantly reduces wiring complexity and centralizes control logic, advancing fully standardized, plug-and-play platforms for next-generation electrified mobility.