Yeah, a common stupid requirement. Perhaps a selling point for any solution would be to deploy a common serialization/de-serialization package that can be used on both the cloud and end point side.
I mean sometimes efficiency matters a lot, but a lot of other times, interoperability is more important.
Text based IO with microcontrollers over tty has been quite a standard thing even decades ago.
> The command-response protocol and binary data format are described in device models generated using DTDLv2 [10], a JSON-based language for describing digital twins. These models are used within the Azure IoT Plug and Play (PnP) framework [11], which STAIoTCraft adopts for datalogging