I was feeling masochistic so I browsed 
for a while, and remembered that all pro-Ukraine folks seem to take this as a fact. I remember trying to look into this and not finding any evidence, and angry libs were not exactly forthcoming with sources themselves.
So besides the initial feint towards Kyiv (which AFAIK is circumstantial at best) was there ever any evidence pointing towards some Russian plan to eventually annex the entirety of Ukraine?
No. As usual it’s projection, as the US has in effect annexed Ukraine, first via the Maidan coup, second via the Bretton Woods institutions of imperialism, and third via lend lease and general gutting and privatization of Ukranian society and productive forces since the start of the SMO nearly two years ago.
What I find most absurd about it all is that Russia has been very clear about their security concerns and proposed solutions for the last fifteen years or so, but these public speeches and press releases are completely ignored in the west.