Well I'm normally having the conversation with US conservatives in the context of responding to them moralizing against a non-US country or a domestic minority, and I'm normally doing it to get them to shut up and feel weird about it. Those conversations are framed in terms of morality for that reason, so what that looks like is the dissolution of every nation whose legal legitimacy depends on the doctrine of Christian discovery

But I frame those conversations morally because our present is so starkly different from any idea of how things ought to be, except for a liberal one. This makes liberals, including conservatives, easy to disorient for a few minutes by disrupting their feeling that things are more or less as they should be

Since you're actually asking, though, I don't know much about decolonial theory. I'm just a white southern-US baby leftist. The best I can do is point you toward Fanon for an examination of colonialism's structure and phenomena