How many gNB-DU are there in Open RAN?

I need your comments on a basic question related to the CU-DU split.
In the 5G specs, when the CU-DU split was proposed within the gNB. Whether the Physical resource blocks (PRBs) allocated to the gNB in a DU are shared among all DUs of that gNB. Or each DU has its own physical resources?

Secondly, How I can get details of the total number of O-CUs, O-DUs, and O-RUs in a 5G open RAN architecture specification as 3GPP is standardizing these parts?

Thirdly, their resource details i.e. how many DUs one CU can have and what are the DU resources, and how many antennas and their configuration in an RU can have?

I am looking forward to your kind reply.

Thanks

What I Have seen in my network is that one VCU has 2 VDU, each VDU is capable of supporting 6 cells, so one VCU supports 12 cells.

However I believe largely it depends on the COTS capacity.

One VCU is assigned one ENB ID, which has cells 1-12.

Then in your network, how many physical resources does a VDU have? If one VDU is capable of supporting 6 cells then how many physical radio resources does one VDU have in actuality?
1024 or 512 or 256?

Kindly let me know so that I can visualize it.

Thanks