Commvault offers support for VCD, but it requires you to configure it from the provider level first before you can protect organizations as Commvault needs to be able to pull information from both vCenter and VCD. 
 

In my case this is not optimal because I have many customers with own Commcell installations which want to use a shared VCD environment as a Recovery target. If I am right this is not possible in this constelation or?

I think it depends who managed the environments because:

• Command Center needs to talk to VCD using provider credentials. So, in case all CommCells are managed by the company who also administers VCD then this could be done by creating per CommCell credentials. 
• Assuming you want to leverage hot-add the access node components needs to be able to talk to vCenter that is part of the VCD hypervisors that leverages a VMware access node. Same applies to previous point.

What is the originating environment? Is it the same VCD platform but different zone/clustert that is designated as a recovery platform.

Here a short description of the use-case:

• Customer has a single Commcell Environment with CS, WS, MA and so on
• Customer copies all the Backups to an S3 Storage
• Customer wants to Restore his VMs/Data from the S3 Bucket to an VCD Environment in case of a disaster. The VCD env is fully managed by a third-party and he has only access through his tenant permissions
• After the disaster the customer wants to bring back the VMs and Data to his own datacenter (copy oder replication)

Assuming the originating platform is VMware or any other hypervisor it is not possible without intervention to perform VM conversions. See also this list: https://documentation.commvault.com/2023e/essential/cross_hypervisor_restores_virtual_machine_conversion.html

I also see a lot of use cases for mentioned scenario and we have had some talks with Commvault to get this sorted. Especially in the Europe region with new regulations coming it might be a big win to have this possibility. Same thing applies to the scenario in where you woud like to be able to restore from/to a different VCD platform.

Anyhow I would open a CMR for it as this might raise the priority at product management.