The issue is more likely a lack of space and the absence of technological capability due to various reasons (backwardness, for example). Russia will soon publish the full list (this is an obvious move) and then relatives will start asking why there are delays in identification when the person has already been missing for several months.
In the first scenario, they would have to bury the bodies quickly (and seemingly pay compensation), and in the second scenario as well, if not for a few "buts." As far as I remember, the lump-sum payment is not 15 million, but it is significant; the rest is paid out monthly over several years.
The new law on recognizing someone as deceased two years after the end of hostilities, along with Ukraine's current status as a defaulting state, suggests that no payments will be made in the near future, bypassing creditors. And two years after the war ends, hryvnias will likely only be good for burning in stoves.