Do you think a virtual card could work with paypal?
It does work but it's pretty much useless to add it, it'll only work where virtual cards(prepaid cards) can he used as payment so if they have the card payment option you might as well just pay with card. Linking it to PayPal does absolutely nothing.
to buy to some seller on ebay
It works, I use virtual visa card and yes, I was selling and buying on ebay. Never ever had problem in buying anything (only wasn't able to buy from chanel.com, gucci.com, sephora and etc, they require billing/shipping adress to be same).
OP it's great for ebay but consider, when you sell item on ebay, you get money on paypal balance.