Right Now the most obvious way to get VC is through calling player inventory. If inventory is too big and you are calling inventory frequently just for VC, the read meter ticks can stack up and increase the overall backend cost.
right now there are many ways to call just vc, i.e through inventory, through login, through combinedinfo api, but there is no specific api for VC.
It would declutter things a bit if there's an api call for Just VC.