Well if you are the highly irritable kind, and a consummate techie , then i suggest explaining to people (higher ups you trust) that you are facing problem entering .NET stream . Seek an assurance (written) that once this activity is done, you can go back to developing apps in android and kotlin.
It is always good to have mentors in an organization who are non-technical so that their perspective enables you to perform better, and rise higher in the organization.
But agreed that Kotlin and .NET are two different streams, and you should be careful about which project you are putting your heart and soul into.
At the end of the day in IT companies, techies are 'resources', and due to staffing compulsions, asking a developer to cross-skill into another area of technology is not an alien concept. The larger (and more professional ) the company , the lesser the likelihood of such a cross-skilling activity being planned, though i can tell you that market needs and industry compulsions, are strong drivers that can influence even the best of organizations towards cross-skilling its employees.