Wrt the ethnic deportations of Tartars, Chechens, and I’m sure others that I cannot think the names of rn, I’m of the opinion that it was a policy failure on Stalin’s/Politburo’s part. Like, I hear what you’re saying that it’s not dissimilar to USian detainment of Japanese Americans, but I think most people here will agree thay was pure racism from FDR and his administration. To the OP, a bit of a problem is that the best scholarship engages with the primary sources (as in most historical study), all of which are in Russian and/or the languages of the various SSRs. So if you’re looking for English-language books, you’re already kinda hamstrung.
Probably unpopular opinion to plug a lib source, but Sean’s Russia Blog (having trouble getting a link to work, here’s a UPitt link. I include cause I think it’s important to note he’s an academic: https://www.ucis.pitt.edu/schoolsandcommunity/resources/seans-russia-blog-and-podcast) is a good place to start. I took his class years ago, he’s a good dude (I think, I ain’t his biographer). I specifically took a course on Stalinism with him, so he’s got lots of sources on that.
Good luck in your journey, the study of history is always worthwhile!
Might I recommend King Leopold’s Ghost if you want a straight up history book of the Belgian Congo. No shade against Heart of Darkness, I think that’s a worthwhile read; but reading KLG first will give you more context to appreciate HoD. Or maybe read it after, idk, up to you