No they don't at anything below sovereign state level. In this case they are not self-determining or self-governing, they are now an annex of Russia.
In any case, you cannot spout self-determination and its status in international law when the very same international law was broken so grievously by a country that had accepted and signed an international treaty agreeing that this region was part of the Ukraine!
Don't you just love Russian trolls - this one lost his credibility from his very first post regarding the nerve agent attack on Sergei Skripal - not the Russian government apparently, just hired muscle in the private sector.