After extensive testing of various microcontroller units, we narrowed it down to two contenders.

We liked the Bluetooth capabilities of the STM32WB, but were underwhelmed by its overall performance. Besides, Bluetooth was already integrated in our wireless components. In the end, the H series of MCUs from STM microcontrollers was the only way to fly.

Beyond sheer performance, we chose the STM32H5 series over the STM32WB series for its enhanced security features. The STM32H5 offers a robust suite of security capabilities including hardware side security. Moreover, the STM32H5's ability to securely store cryptographic keys was something we hoped we could integrate, especially when considering applications like Two-Factor Authentication (2FA), where the integrity and confidentiality of stored keys are paramount.