Do note that another term for absolute anonymous donations is "funding terrorism". So good luck hiding your donations entirely.

I suspect a sibling comment is correct - buy a visa/etc giftcard (perhaps with cash) and use that to donate online if the recipient accepts online payments - or send the card details via email, or the card via snail mail?

Or more commonly "money laundering"

That's a valid perspective, thanks for mentioning.

> buy a visa/etc giftcard

I like that suggestion the best as well.

Not OP but if I wanted to donate without revealing identity to the recipient, what are my options?

Depending on the recipient's fraud checks you can simply use your credit card but use a fake name & address; if they don't decline the transaction then that's all you have to do.