I would add the note that while it took some time to pacify Mariupol, that's because it was the home of the Azov Battalion, and those fanatics used human shields and dug in to the basement of Azovstal. Scott Ritter noted that they also began with strength much higher than commonly realized, up to 20,000 (two divisions!)

The point is, I suspect resistance in cities such as Mykolaiv, Odessa, and others on the way to Transnistria will be quite substantially lower for a variety of reasons, not least of which is the lack of Azov's "espirit de corps".