Why would users care if you're using the same type checker as them? Surely they're not expecting all their imports to be instrumented for running redundant types checks?
Users do not care about that, but they want to not see type errors or warnings when they integrate your API in their code.
That’s why you want to run their type checker on your API. you cannot know what “their type checker” is, so you want to run all popular type checkers on your API.
Sounds like a them-problem. Their type checker can accept my declared typings for my public API, or they can override it with their own custom type stubs if they have objections.
That’s why you want to run their type checker on your API. you cannot know what “their type checker” is, so you want to run all popular type checkers on your API.