Insurgency risk is high even in Russia and even not organized by Ukr government.I would seriously not assume that the whole country is as motivated to fight (in the areas occupied) as western media has led us to believe. 1) All the young people are mostly gone from those areas anyway and 2) the ones who were fanatically pro-UKR probably went west and joined the AFU already. Outside of some low level terrorism, I doubt there will be a serious insurgency in those areas.
You are correct that in areas where Russia had advanced ....normally thinking ukr civies had did all the best to fled ( relocate ) IF they were able.
While even Russia does have Ukrainians and 1/2 origin ukr ...even Rus citizens living in Russia since birth.
Sabotage risk in Russia is very high.
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IMHO you are thinking that it is just colonial war like other empires had ....
It isn't , it is fight for russification and mandatory deUkrainization.
Therefore ofc willingless to resist is higher than than in some simple colonial wars.
Also most likely bad treatment of POVs like Hitler did....also increase willingless not to give up.
Shit with revenge and so on is just warming up.