A lot of the heavy lifting in US law is being done here:
https://www.law.cornell.edu/uscode/text/21/823
TLDR it's possible to get a license to do research with schedule I drugs, but the licensing hurdles are higher than those for prescribing even schedule II drugs (which in the US includes cocaine and methamphetamine). Those hurdles could be lowered in various ways, perhaps with reference to the general procedures for researching new drugs described here:
Re: "change the medical classification of several drugs, such as LSD, MDMA (‘ecstasy’), psilocybin (‘magic mushrooms’), so it’s much easier to conduct research on their effects and use them in treatment of mental illnesses."
I'm not sure about other countries, but under the US Controlled Substances Act, theoretically no drug is off-limits for medical research. The problem is that getting approval to conduct research on schedule I substances is very difficult. So the solution doesn't necessarily require rescheduling—Congress could pass a law making it easier to get approval.
When you say that US and Russian nuclear targeting doctrine has changed, I assume you mean "changed since the 1980s", since you reference research on nuclear winter. If that's your claim, your evidence for it appears to rest on a series of misunderstandings.
One of the most direct pieces of evidence I can give that this claim is wrong is comes from a report by the Federation of American Scientists, which shows how the categories of nuclear targets in US war planning have not changed significantly between 1976 and 2009 (p. 6, table 5):
http://large.stanford.edu/…/ph2…/connell2/docs/fas-feb10.pdf
At least as of 2009, categories of nuclear targets include "Military and national leadership" and "War supporting infrastructure", which are especially likely to be located in densely-populated areas where large amounts of "collateral damage" would be inevitable.
This does not mean that any US use of nuclear weapons *would* include such targets—since the Kennedy administration, US nuclear doctrine has emphasized flexibility and giving the president a range of options for how to use nuclear weapons if he chooses to do so. But use of nuclear weapons against e.g. Moscow is almost certainly among the strike options currently contained inside the president's "nuclear football").
Of course, reductions in sizes of nuclear weapons does matter somewhat here. Detonating a 400kt weapon directly above the Kremlin won't kill as many people as detonating a 9 megaton weapon in the same location. But the 400kt weapon is "small" only relative to the 9 megaton one, 400kt is still much larger than the weapons used on Hiroshima and Nagasaki.
Some of the mistake seems to come from not understanding what military planners mean by phrases like "targeting civilians". At first, it might seem very reassuring that the US military says it would not under any circumstances target civilians. However, when the United States bombed Hiroshima and Nagasaki, it claimed it wasn't targeting civilians even then—it claimed it was targeting depots, ports, and war industry, and that the civilians killed in the atomic bombings were merely "collateral damage".
By similar reasoning, in the event of a war with Russia, targeting Russia's "leadership" would not be "targeting civilians", even if it involved detonating one or more nuclear weapons in the center of Moscow.
There's also a risk of being mislead by the euphemism treadmill. For example, during the Bush administration, there was a proposal to replace the term "countervalue targeting" with "critical infrastructure targeting" in US nuclear doctrine. This proposal got some pushback, and in the end *neither* term was used. However, the dropping of the term "countervalue targeting" does not seem to have reflected any change in targeting practices. Both sides of the terminological dispute seem to have agreed that targeting "infrastructure" was legitimate. See:
https://www.armscontrol.org/act/2005_09/Kristensen
Furthermore, the discussion of whether Russia would engage in countervalue targeting seems to seriously misread the cited sources. The target list discussed here:
https://www.popularmechanics.com/…/a26536357/putin-new-nuk…/
is a target list for new nuclear weapons Russia is threatening to build, not all Russian nuclear forces. Even more troublingly, this article:
https://www.tandfonline.com/…/full/10…/00963402.2019.1580891
is cited as showing Russia's nuclear arsenal is designed for countervalue targeting, but the article describes one weapon currently under development in Russia as intended to create "areas of wide radioactive contamination that would be unsuitable for military, economic, or other activity for long periods of time".
I have no doubt that Russian nuclear doctrine, like US nuclear doctrine, includes counterforce targeting, but that doesn't mean it includes *only* counterforce targeting.