Hey @PatEnergy - great question. (and thanks for the tag @BérangèreL 
)
In my experience, I’m in agreement that calculating ARR with the granularity you’re looking for isn’t the easiest in HubSpot. I don’t have a simple solution here, so I’m checking with my colleagues and I’ll see if anyone has a client they’ve solved this for. I’ll share it if so.
In the meantime, here are a few resources to possibly help: