Fabric Capacity Allocation

Hi jashfabric 
Thanks for using Fabric Community.
Unfortunately, there's no fixed ratio or priority for CU allocation in Microsoft Fabric when multiple artifacts (notebooks, pipelines, Dataflow Gen2, and Power BI) run concurrently. But you can use the Microsoft Fabric Capacity Metrics App.

The Microsoft Fabric Capacity Metrics app is designed to provide monitoring capabilities for Microsoft Fabric capacities. Monitoring your capacities is essential for making informed decisions on how to best use your capacity resources. For example, the app can help identify when to scale up your capacity or when to turn on autoscale.

For more information please refer to this documents:
https://learn.microsoft.com/en-us/fabric/enterprise/metrics-app
https://learn.microsoft.com/en-us/fabric/enterprise/metrics-app-install?tabs=1st
https://learn.microsoft.com/en-us/fabric/enterprise/metrics-app-compute-page

Hope this helps. Please let me know if you have any further questions.