“The eeprom MAC address is quite new for me. I think there should be a “default MAC” in the firmware, because it works without this eeprom populated, but I only tried with one instance.”
– Yes, if the firmware does not detect the existence of 24AA02E48 chip, it will use a default MAC.
It’s not clear to me which particular idea you are asking my opinion on. I think you meant the general idea of a cloud based service and polling? That is a common way to implement cloud connection — it might be a bit slow due to the nature of polling (compared to some other options), but it should work as you described.