I do not agree about decapitation strike. Capturing Kiev won't do anything since current Ukraine is not controlled just by formal figures like president, government or parliament. The problem IMO is netcentric Nazi entities like Azov which formally are controlled by government (ministry of internal affairs), local authorities or APU headquarters, but in fact it is either other way around or they are independent, at least in military terms. I believe it is the reason why Zelensky wouldn't have been able to fulfill his electoral promices - he never had any power being Kolomoysky's figurehead and if he tried, his efforts would've been just ignored by local governors and in the end he might have had an 'accident'.
So if Kiev was captured or surrounded and central government surrendered or rendered inoperable, the orders to local governors would've started to come through this network and it would've been enough to mount active resistance at least in Sumi, Chernigov, Kiev and Kharkiv regions. Maybe it would've caused defences in Donbass region to crumble (and it happened to certain extent anyway, causing loss of Mariupol and formation of land bridge between Crimea and continental Russia).
This netcentric structure actually the hardest challenge since without destroying it the objective of 'denazification' cannot be fulfilled, and the structure itself is very resilient and has major control nodes outside of Ukraine (CIA or/and MI-6 controlled, maybe some Polish special services added).
