There's this youtube channel (The Math Sorcerer) that does reviews of old or rare university and school textbooks. They have a lot of content on soviet books, including a lot of maths (the guy running it is a mathematician obviously). Might not be exactly what you are looking for, but there's a lot of interesting information and names of authors, topics you might want to look up. Also great for seeing the environment Soviet scientists worked and trained in. The big takeaway is that Soviet textbooks were hardcore and to the point, as well as packed with information, and with a big focus on sharing knowledge internationally.
Mathematics
I recall The Math Sorcerer saying that mathematics historically were printed in four languages. These languages being English, French, German and Russian. The USSR put a lot of resources into STEM research and even made the fruits of this research available to the public to read and learn from. In the USSR, you used to be able to get cutting-edge academic level textbooks and theory for cheap while in the West, just reading a single article from an academic journal can cost you $50.
It's a really big shame because many people go to college and are completely shut out from the academic world after they graduate. The USSR took amateur science more seriously.
Yeah, I already knew The Math Sorcerer, it's very good but I'd also like to know about math reasearch in the USSR.