Bitrefill now has Prepaid Mastercard gift cards for the US.
I can't buy it because of my location, so I can't see the real price, but the "estimate" for a $1 prepaid mastercard is 4279 sat! That would mean a prepaid mastercard with no overhead, I thought it usually costs at least a few bucks per card.
Try using Tor with a US exit node. Seemed to work with me when accessing a previous Walmart card of mine.
It should work as long as the website is not banning tor, or there is no Cloudflare with annoying captcha.