I wouldn't bother them with any trivial stuff for which you can easily find a reviewer elsewhere at this point, but if something really requires high level of expertise and you know a really good specialist in Ukraine, I see nothing unethical about asking (but asking is not a synonym of insisting!) if you manage to establish a contact, which, as Massimo noted, may now be a bit more difficult than usual.
In general, my opinion is that even in the peace time, people in difficult situations are uplifted if someone trusts them with good interesting work and get irritated if someone asks them to review patented junk the editors were too lazy/busy to reject themselves. So just be more selective than before the war.
As to "bonus question", play it by ear. There is no obvious answer for that. When my Ukrainian friends talk about "Russians", I sometimes make a point of reminding them that I am one of those (nevermind that I'm on the side of Ukraine in this war and that I have an American citizenship for over 15 years by now). That, nevertheless, creates no offense on either side, and we discuss freely many things way more "sensitive" than pure math. When the Ukrainian Rada recently made a move to prohibit citations of Russian authors in Ukrainian papers, many of them signed a letter of protest and called such move "idiotic". There are a lot of subtleties here beyond the "us" versus "them" division by the nationality alone.
Again, exercise caution and common sense but, IMHO, the only worldwide guild that should finally file for bankruptcy and be disbanded as the result of the recent events is that of politicians. Mathematicians should try to stay together as a guild (though many individual relations may be rather strained now). I don't know how to facilitate that and it is obviously impossible to do it by force or through logical persuasion alone, but some gentle nudges here and there may go at least some way.
Just my two cents...