qpc VS FreeAct

The QP/C framework already seems to solve all your problems, so if you're asking how to organize your code, this is the best answer you can get. It also seems a little inconsistent that you are taking FreeRTOS, so you are not considering writing your own RTOS kernel. But at the same time, you are rolling out your own event-driven framework as though it was somehow easier, which is not the case and probably quite the opposite.

HSM-test code in C (on GitHub)

Perhaps you could take a look at "FreeACT" project on GitHub, which shows the first steps in building an "Active Object" framework on top of FreeRTOS. The "FreeACT" framework currently does not have event management yet, but you could add it. This is an open-source project permissively licensed under the MIT license and everyone is welcome to contribute.

Finally, for anyone interested in specific code, there is a FreeACT project on GitHub, where you can find a rudimentary Active Object Framework built on top of FreeRTOS.

You will also need to be careful with blocking, because this clogs the event-loop that each of your tasks will be running. Among others, that means that you cannot use vTaskDelay(), for example. Instead, you would need to replace all such blocking mechanisms with event-driven equivalents. For example, you need to implement time-events instead of the blocking delay(). Here, you might want to take a look at the "FreeACT" minimal real-time framework based on FreeRTOS.