Combining a Linux capable CPU and MCU is not new or that weird... I think a Cortex A9 and Cortex M4 appeared on a combined SoC on the IMX6 platform around 10 years ago.
Plenty of use cases in embedded!
Heck, the Raspberry Pi 5 does this. GPIO is handled by an MCU that is effectively a Raspberry Pi Pico.
Heck, the Raspberry Pi 5 does this. GPIO is handled by an MCU that is effectively a Raspberry Pi Pico.