If that's the case, then I suggest not to transfer the funds from SGD bank to USD wallet as you're bank may still charge you cross border fees. Instead, you can do the following,
  1. Top up your SGD Wallet
  2. Add all subscriptions and use the SGD wallet to pay. Even if you use the SGD wallet, you'll still save money compared to what you would pay using an SGD Credit card.
  3. Once your USD bank is ready, you can move the subscriptions to the USD wallet.