Not sure what you mean by "pending datastore capacity" in this context. If you're asking about free space on the same extent, no I don't think that's exposed anywhere. It's of very limited use anyhow as that tends to only be for host-local block devices anyhow, which should really be avoided if at all possible.
"Not sure what you mean by "pending datastore capacity" in this context." - Sorry if it wasn't clear, hopefully the below clears it up
As per the screenshot, If I add storage to an exported VLUN on my SAN (say 512gb), then rescan the storage in vCenter, the VLUN as it shows up in vCenter (as a datastore) will show that there is 512gb available storage which can be added to (or used to expand) the datastore. Note that the VV is exported to a cluster and not a single host.
Is there any such script which which can scan all datastores in vCenter and check and see if there are any expansions pending, something similar to the table below:
Datastore Name Currently Available Actual HP7400_Datastore1 2560gb 3072gb
I know I could go eyeball between my SAN and available datastores in vCenter but I was wondering if there is an easier way to do this.