Great question - I think the best book of active dissent would be Putin’s Russia by Anna Politkovskaya - she was right on so many counts, and she does a good job of revealing hard truths through storytelling - hard truths she ended up paying her life for.

But if it’s on dissent, I like the Rebel by Camus or L'Homme révolté in the original French (which comes off stronger/more poetic) as a meta-analysis of dissent and rebellion itself. I have my own opinions on Camus and his positions - and the contrast/foil of Sartre which he is often placed in counter-position against. But perhaps saved for another time haha.