This is a bit of a double edged sword at the moment. The fist problem is the delivery date eBay provides to the buyer when they purchase the item, the second is the current shipping situation. If the shipping information was uploaded when you shipped the item then check to see where the package is. The buyer cannot open a INR case until after the package is past the delivery date. If your shipping information shows the package being delivered provide that information in the open case and you will not have to refund. If the shipping information indicates the package has not been delivered and it's past the delivery date then either you can refund or eBay will do it for you automatically.
This is the catch 22 and there are without a doubt buyers who are watching the shipping like a hawk and taking full advantage of the current situation. If the buyers money is refunded and the package is just delayed in the delivery process they will ultimately get the item, they already have their money back and they are under no obligation to either repay you or return the item other than any moral or ethical obligation they may feel they have.
The only hope you may have if you refund is to see if you can have USPS intercept and return the package. There is a cost for this service and you would need to see if the value of the item is worth the recall attempt.
