I'm pretty sure this law won't work among Russians in general, so tourists are safe. I think even if it did work, tourists wouldn't have to use Russian software because it would be way too odd. Russia is a great country to visit, so I don't think it would do something like that to stop the tourist traffic. Anyway, it's pretty easy to check if there are any restrictions like that for foreigners, so I'm planning to get russian tourist visa via https://www.russia-travel.com/visa-services/ , and hopefully, I won't have any problems with my iPhone.