What you say about the Russian actions in Ukraine is true, the question is would they prefer full annexation if they knew NATO wouldn't intervene? I'd say they probably would. If the goal is security, not many things more secure than saying "this is our territory now", it would also enable a lot of direct control instead of relying on manipulated chaos that can always blow up in your face.
>prefer full annexation if they knew NATO wouldn't intervene
You mean of the entire Ukraine? Because it would cost them more than it's worth. No Russian actions since 1991 have so far indicated that they actually want to conquer any foreign area not inhabited by a Russian speaking majority or whose population would be likely to actively resist such occupation.
Stirring up ethnic border wars is a cheap way of sapping the strength of regional powers. The British Empire honed it to a fine art.
From a more cynical, pragmatic "realpolitik" perspective one can view Russian actions in Ukraine as largely defensive. From the collapse of the Soviet Union Ukraine largely functioned as a semi-protectorate of Russia, even before 2014 Russian probably had significantly more troops stationed in Crimea than Ukrainians themselves since their black sea fleet is stationed there. After the events of 2014 Russia saw that long-term they are likely going to loose Ukraine anyway and basically decided to cut their losses and at least maintain the control of Crimea. It's not like Russia actually wants to fully annex the regions in eastern Ukraine their currently fighting over, they just want a semi permanent conflict which would destabilize Ukraine politically and to ensure that the Ukraine could never join NATO (and likely the EU), since NATO accepting Ukraine would be basically equivalent to them declaring war on Russia..