Yes. The last person that the United States executed for desertion, Eddie Slovik in 1945, was tried in a military court, found guilty, and executed.

I assume that Russia would have rules for the same. Whether they are followed is the question.

But it’s a special military operation, not war 😉

They’re meant to, but personally I don’t trust anyone of any nationality that joined the military or the police, to do the right thing.