If this article is to be believed then, Chakra-II will not come with any Russian personnel on board. That is good. We need to operate this on our own. But the utility of this sub in training Indian naval personnel is also questionable. Naval personnel on Arihant and its sister ships can carry out mock drills on firing of K series of missiles. Training naval personnel w.r.t nuclear reactors can be easily done on shore based facilities.
Chakra-II is a SSN. It is meant to attack targets like USN CBG or other SSBN and possibly SSGN. After 1971 - USS Enterprise fiasco and non withstanding all the hype about India-US strategic alignment, it would make sense for IN to have assets which might make any eventual repeat of 1971 USS Enterprise saga redundant.
But look at certain facts. This lease is for 10 years. This is an attack submarine not a deterrence based boomer. Unless India plans to build SSBN first and later on SSN, then only does it operationally sense for India to go for Nerpa. It has been insinuated that India plans on building 5 nuclear submarines. Assuming that it will take 2-3 years for us to build a nuclear submarine, we might be in a position of having SSBN in our inventory but not SSN by the time this decade runs out. But throw in nerpa and the calculus changes.
Technologically I understand nerpa gives us access to some cutting edge nuclear submarine tech. But from a purely operational perspective, considering that the lease is for a decade, this submarine says something else entirely. And if it is to be believed that this is only first of the two or three SSN which will join IN, then it does appear that IN is planning something different and training is not the first purpose of this SSN, i.e. nerpa/Chakra-II.