I am from Ukraine, and we have KGB archives opened for a while now.

It is a massive amount of information and it is studied rigorously by a lot of researchers. Unfortunately, most of the information I consumed are in Ukrainian. For example there is a book in Ukrainian released just few years ago from one of those [0]. But basically any researcher can get access to the whole archive and domestic ones wrote a lot of material. I am sure that it will get more popular on the west as well, while people will get understanding of the systems at work.

As far as I know Timothy Snyder is well known for his researches into Russia in his books such as [1]. However I've read only excerpts from it as we have better material in Ukrainian.

West generally doesn't understand Russia, it overestimates its military power and underestimates its propaganda influence. It also completely misunderstands its culture. Also west have a history to dismiss the voices of countries who do know Russia very well. But it is changing bit by bit.