Having two cores can also be useful in configuration when the other core is used as a “co-processor”, though. There is a very nice project
https://forums.mbed.com/t/marquesas-mbed-based-open-source-digital-gauge-cluster/
published by George Beckstein, running on STM32H745BI dual-core microcontroller:
The intent behind the dual-core MCU is that the M7 can run an application with all the UI code (way more surface area for potential bugs) while the M4 handles real-time functions like collecting data from other ECUs over the CAN bus, reading attached sensors, driving analog gauges, among other tasks. This makes it easier to harden the CM4 application handling all the critical functions of the gauge cluster.