Just to establish the premise - The solution is for avoiding unnecessary tax and not tax evasion.

That said, Virtual Credit Card and Gift cards are not interchangeable under most jurisdictions i.e. If there's a law which makes you pay taxes if you receive 5 USD as donation, Then certainly receiving that 5 USD as virtual CC is also taxable.

Gift cards  or even physical gifts on the other hand are specifically tax exempted as their purpose is constrained.

So I think Acme Co. should directly buy credits from various infrastructure services and deliver that to their customer  (i.e. project builder) depending upon how much a donor pays. Getting the services on-board is the real work here, Technical implementation is straightforward.