David Anthony Durham's Acacia is pretty much all about grappling with a thinly veiled fantasy metaphor for American imperialism.
Aliette de Bodard does a lot of interesting SF work in this area and I know she does fantasy, but I don't know if it carries over.
I have not personally read but have heard good things about the way The Traitor Baru Cormorant engages with imperialism, which may or may not be the same thing.
I also really enjoyed Karin Lowachee's Gaslight Dogs.
Otherwise most of the fantasy work i've seen in this space is about shifting the tradition of fantasy that it's working with, which feels like not quite what you're looking for.
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Aliette de Bodard does a lot of interesting SF work in this area and I know she does fantasy, but I don't know if it carries over.
I have not personally read but have heard good things about the way The Traitor Baru Cormorant engages with imperialism, which may or may not be the same thing.
I also really enjoyed Karin Lowachee's Gaslight Dogs.
Otherwise most of the fantasy work i've seen in this space is about shifting the tradition of fantasy that it's working with, which feels like not quite what you're looking for.