Also, I’m not sure that this statement is correct…
I’m guessing that what you mean is that Atmega328P based boards don’t support dynamic provisioning or OTA updates via Blynk.Air ?
If you had a previously functioning Blynk product using the Atmega328P under Blynk Legacy then I don’t think that there is any reason why that same product shouldn’t operate with the same functionality under Blynk IoT.