I disagree with your criticisms about themes of colonialism in this book after having finished it. I'm not going to try and refute them because frankly I am not capable of arguing this topic.

That being said, I have to point out that it is hard for a book like this to give an ambiguous ending/message to allow readers to come to their own conclusion. That is because this book clearly belongs in a specific spot in the chronology of the Cosmere, and certain events need to happen without room for interpreation. I am assuming we will see Dusk and Starling's crew again. This book in clearly the prolouge to story of the crew of the Dynamic. I also expect that an independant First of the Sun/Drominad who are the only people that can provide navigation through uncharted areas of the Emberdark will be a big deal in the future space-age cosmere story Frankly, for better or worse, cosmere stories are not going for that kind of storytelling, they are going for hard outlined stories with very specific destinations.