You can take a two-way radio anywhere, and it will work, but often not legally. For example, the FRS/GMRS radios that are prevalent in the USA are not compatible with the European standard PMR446 and cannot legally be used. Technically a PMR446 compatible radio can be programmed to GMRS frequencies, but it would not be legal to use it as such in the USA. Likewise the ISM (900MHz) band radios I use in the USA cannot be used legally in Europe. Basically, it's going to be a world of paperwork if it's even possible to get a two way radio to work the way you want.
You may find some crossover in amateur radio bands, with the associated licensing requirements.
If mobile/cell phones are not an option, I would be looking at satellite messengers. I have a Spot X Messenger and Garmin inReach I use -- their price will likely be north of $100 unless you can find some used ones on eBay, but they work well for communicating well off grid. Note at least for inReach you will need to register before using in Russia.
Here's a good thread about satellite messengers.