You are a little wrong. They also accept all tokens on Ethereum (ou tokens ERC20)
This is indicated in the list. It turns out they take thousands of currencies and believe in their future)
Accepting donations in a currency =/= believing in its future. I would call it a stretch to say that UNICEF "believes in the future" of all ERC20 tokens when the vast majority of them are trash. But if they can sell them for Bitcoin or fiat, then sure, donate away.
They also provide links on that page so you can mine on their behalf.