How to extract only highest metal Power/Ground/Bulk routing from top-level hierarchy using SKILL/Python in Virtuoso Studio IC 23.1?

Hello Cadence Community,

I am using Cadence Virtuoso Studio IC 23.1 and I am trying to create an automation flow to extract only the highest metal routing shapes for Power/Ground/Bulk nets from a top-level layout.

I want the script to automatically identify Power, Ground, and Bulk nets from the layout/database, without asking the user to manually provide net names.

For example, the script should automatically recognize nets like:

Power nets: VDD, VDD1, VDD2...etc.
Ground nets: VSS, VSSA, VSSB,  etc.
Bulk/Well nets: NWELL, DNWELL, BULK, etc.
I am looking for the best way to identify them using net properties, terminal types, global nets, inherited connections, or any recommended Virtuoso database API.
Main challenge
In some designs, the top-level cell may only contain pins for these nets, while the actual metal routing is present inside lower-level sub-blocks.

So, I do not want to extract only the top-level pin shapes. I want to traverse the hierarchy and identify where the actual routing metal exists for the auto-detected PG/Bulk nets.