Buying GV on Amazon used to get Merchant as "Amazon" which regarded as Amazon spends but since the beginning of this month get as "Amazon pay India". Not sure points will be awarded or not.
Another way is purchasing GV from SmartBuy/PayZapp but there is a fee for it.
Or else check Amazon Pay rewards section sometimes there are user specific offers 100 or 105 cashback on purchasing 3k GV again the transaction may reflect as Amazon or Amazon Pay.
Or else directly pay using your CC as it gives 10X points on Amazon transactions. Look out how the transaction is going through.