That Flash budget is sized to hold a full USB Power Delivery protocol stack plus the application-layer policy engine, with room for field-update staging. The Cortex-M0 gives you a single-cycle 32-bit datapath for the PD packet processing and state-machine transitions, while keeping the power profile low enough for bus-powered designs.
Interface set and I/O count
The I²C and SPI ports are the typical control channels for port partners; the UART is useful for debug logging during bring-up without consuming a USB endpoint.
Package — 96-ball BGA, 6x6 mm
The EZ-PD CCG5 series is Infineon's current-generation USB Type-C controller family, so roadmap continuity is solid.