I'm working in the IIoT domain too. Your workflow is interesting towards the end. Any particular reason, why you don't write it to some db like Timescale or Influx at the end without any prometheus conversion?
TimescaleDB is perfect if you also have relational data that you need to join with field data to the point that there no pros of using anything else for this use case, say you have 100000+ sensors and you need to group them by the customer site relations while aggregating per day statistics.