Yes you can donate using Bitcoin. Just find the right agency that accepts it.
I am not sure if this is a legitimate one, but you can check it out.
https://standwithukraine.com.ua/donation/cryptoI think that's the best part on having Bitcoin although there are still very few retail shops that accepts it. Donation is not a problem though. Bitcoin is global. It has no boundaries unless they ban it in their country. But for those who needs help, I don't think they not accept Bitcoin.