So I can give a bit of background on the historiography of Soviet crimes and atrocities - the tl;dr is that Snyder's number is about correct, but Snyder is not a very good historian and I would not use him as a main source for this.
The grand old man in this context is Robert Conquest, who wrote the definitive works of his day in the -60's and -70's, The Great Terror and The Harvest of Sorrow. Both are eminently readable to this day and I highly recommend them to anyone interested in Soviet history.
I would, on the other hand, highly recommend just throwing Conquest's works straight into the dustbin. While there is
some stuff of interest in his works, it is so entwined with Cold War anti-communist propaganda (which he was, after all, employed to produce) that it makes his works useless as historical reference. It's probably more work to check all his claims and sources to separate fact from fiction than to just collect the necessary primary sources to build your own view of what happened. His works are a net negative, and the stuff that actually is factual and accurately represented is outdated by the opening of the Soviet archives anyway, just like most other works written before the Soviet archives were opened.
The more vicious aspect of this, in my view, is the construct of the "Holodomor" ("Death by Famine"), widely promoted by Ukranian nationalists.
It even appears that the term "Holodomor" was deliberately coined to be similar to "Holocaust".
I definitely think that deaths as a result of Stalinist-style collectivization are a category worthy of study
Which deaths would that be? Ascribing the famine to the collectivization and mechanization of agriculture (CMA) is a
cum hoc ergo propter hoc. For all you know the famine would've been even worse without the CMA, and the CMA might have
saved lives instead. It seems even the more likely case. The theory that the CMA caused the famine fails on several levels:
1. Since the 1933 growing season continued the CMA along the same lines as the 1932 one, but with even less "experienced peasants" (since many starved in the famine) and even more unexperienced people brought in to do the farming work, the theory would predict the 1933 harvest to be even worse. Yet the 1933 harvest was the largest of the period.
2. Statistically, pre-CMA harvest failures occurred every 3-4 years and full-blown famines every 10 years, post-CMA there were none of either anymore. The CMA is strongly associated with the
end of food insecurity and famines in the region.
The theory that best explains the famine (or at least the harvest failure leading up to it) is environmental causes, and since by point 2 above the CMA is statistically associated with security against such events (rather than the opposite) it seems more likely that the famine would've been even worse without the CMA. So maybe it's not the deaths as a result of Stalinist-style collectivization that are a category worthy of study, but the lives saved as a result of it.