AFAIK there is no more such an overnight-as far as Milano then change. So that means 2 traveldays to use. Or even via München/DE=takes much longer, but longer night in train too. As always: use a travelplanner, on trains you are assumed to have the basic knowledge.

IT takes the anti-covid measures very, very strict-understandable re its history in having the very first big wave. So that also means they still have very strict rules on using overnight-and yes, you have to wear a specified type of mask all the time and change it every 4 hrs to a new one.

I do not quite see what UKR has to do with this. You may meet a few groups of ladies+kids coming from there and on the way to some safe place. In most countries they can travel for free