I think the best way to go is to use a NGO from your country or an international one, where you know that they can help in the Ukraine. If you trust them you could engage there.
I personally wouldn’t send money to any bank account that I can’t verify, based on a story I can’t verify.
Lets not forget that before “the war, I abhor” the Ukraine was one of the countries known to have Internet criminals, phishers, spammers and social engineering hacks. I am sure they did not disappear, perhaps only got more desperate.
Olegh has been active in this community since 2016. In fact, in his first post to the group he kicked off a thread about Cyrillic characters in tiddler titles for static file generation that was one of the triggers for the addition of the “slugify” operator.
I can’t give useful advice on the best way to help Olegh, but I think I can at the least vouch for the fact that he is not a scammer.