As an engineering / hiring manager looking at someone who is starting out, I (personally) assume that languages, frameworks and OS are teachable skills, and look for flexibility, passion, drive, humility, willingness to learn, grasp of engineering principles … and a candidate demonstrates that through their use of (say) Android Dev. You need to have credible skills but I don’t expect a person at the start of their career to have it all down yet.
It would be good to get an appreciation of different “families” of language (strongly typed vs loosely typed, eg Kotlin vs Javascript, and/or procedural vs functional) Mobile dev, Web dev and backend dev are all different worlds and it would be good to appreciate the differences, and strengths. You will always find yourself on teams with other people, and this helps connect with folk working on other parts of the project!