Make sure the gift card is in the right currency. I have accidentally sent Amazon US to a provider in the past.
I have used paypal in the past Many providers ask for ID and know who I am anyway.
When PayPal is not an available deposit option, and since I can’t do e transfer, I just email them I would like to send the deposit by gift card and they will tell me which one they want and how much. One provider was very sweet and even sent me the link for every gift card options