I doubt there isn’t some Russian-language one, but often I find myself wanting just a quick glimpse about some soviet thing, usually technology (space program, computing, maths, logistics), but I have to choose between NATOpedia’s “Joseph Stalin considered the computer an evil product of capitalism” or reading a whole book about it. And my reading list is too full already.
I know the prolewiki covers a lot of the main interesting ideological points, but sometimes I just want to get the cliffnotes about some researcher or even more boring stuff like food.
I don’t know of any English ones, but you can machine translate articles from the Great Soviet Encyclopedia.