Choose a learning goal first
If your first goal involves Wi-Fi or Bluetooth on a small development board, ESP32 is a useful family to investigate. If you are exploring particular peripheral, timing or board requirements, STM32 offers a broad set of devices to examine. Neither name identifies one fixed collection of features.
Check the exact chip and board
Wireless support, pin availability and peripherals vary by part. Compare actual part numbers and development-board documentation, not a family label. Also check what programmer or debugger the board needs and whether you can follow a supported getting-started path.
Use the tools to understand behavior
ESP-IDF is Espressif’s development framework; STM32CubeIDE provides development and debugging tools for STM32. The ability to build a minimal example, inspect output and reproduce a problem matters more initially than the number of features on a specification sheet.
What is available at Hexa Firmware Labs?
The published advanced course covers ESP32 and FreeRTOS. A dedicated STM32 syllabus is not currently published; enquire about availability before planning a batch or buying hardware. The beginner PIC18F / ATmega course provides an alternative route into peripheral fundamentals.