Yeah it would depend on APIs and the support of charities should be based on the merits of supporting that charity, not if they for some reason have enough money to invest in a fancy API.
My view is, you don't need an add-on for this. If there is a charity or charities you wish to support, set up a seperate PayPal (or whatever) account, have your account upgrade money go into that and then make periodic donations yourself to the charity/s you wish to support.
hmm, true, that would indeed be a easier, I was simply hoping for a more automated way, but you are completely right in that it would probably just end up limiting what choices of charities are available.
Unless someone else really wants this, feel free to close and/or remove this thread.