In some weird sense, after all the nuclear threats, the least risky option to carry out the threats for Russia would definitely be to nuke itself. Russia has a lot of territory.
I think starting from Siberia would be the safest option as it would probably not result in a fallout on foreign soil that could potentially trigger any "articles" of any sort, either.
Yesterday, a Russian paramilitary group conducting raids inside Russian territory in Belgorod oblast who had captured a number of Russian soldiers and border guards, asked Prigozhin if he'd like to swap for them a lieutenant colonel Wagner had captured for shooting Wagner vehicles near Bakhmut while drunk. The paramilitary group had failed to convince the governor of Belgorod oblast to meet in order to negotiate about the hostages and came up with this option.
Here's the Russian lieutenant colonel (a brigade commander) being interviewed by Wagner on camera:
It's definitely getting wilder day by day. There is no shortage of armed organizations in Russia who have no love lost for one another. Prigozhin has openly and very harshly criticized Shoigu and Gerasimov multiple times and accused them of depriving Wagner of ammunition and supplies at critical moments. He has once even criticized Putin himself. Kadyrov's Chechens are not on particularly good terms with Wagner, either. Putin's forces do not have unity of command because as is customary in dictatorships, he has to keep any particular armed organization from becoming too powerful to prevent any one of from rallying too much support to be a risk for his rule. This type of a system can remain in a dynamic balance if the dictator handles everything skillfully. But something unexpected and unfortunate can always happen that derails everything. At that point, an ugly mess could ensue.
The Special Military Operation seems to be turning into a right mess.