It depends, I think what you said was more true when the war started. Now most of the Ukrainian nationalist are dead, and lots escaped abroad, understandably. But tbh it matters little, controlling the terrain is secondary for Russia, the primary objective is to install some sort of puppet in Kiev that they can control, a bit like Lukashenko in Belarus. They might end up annexing just the areas less prone to revolt (basically what they control right now) and then control the rest via puppet.

Tbh, I think it's pointless to discuss this matter in detail, whatever the case, insurgency or not, there is no good way out for the Ukrainians, which was my point.