Here's how you can enhance your skills as a mobile app developer in late career.

Mastering Fundamentals is imp for any topic to begin with: For a Mobile Dev: 1. What is a lifecycle? 2. How to manage multiple screens and multiple screen sizes 3. How to interact with UI components? 4. How to write scaleable code? 5. How to use the device power like data storage etc 6. How to write test cases 7. What are the edge cases you can think of as mobile dev, as a lot of things can happen while you use a application 8. Networking, Loading of data, Offline Support, No Internet errors and similar things should be handled as Mobile Dev

The best way to be good is by grasping the root very well, and understanding the core basics of programming and mobile app development, with that you can easily dive into any mobile development tool. As a native mobile developer using Java and XML, switching and writing using kotlin was easy for me because I already understand the core basics of programming and android app development, and switching to cross-platform using flutter was even simpler because I just need to learn is the syntax and every other thing is simple. So it is important to grasp the basics well then you can fly around any programming language of your choice at anytime.

Contributing to open-source projects teaches us how coding standards and practices differ from our own. It also enhances our ability to write clear and effective comments for specific code blocks or functions. Writing test cases for mobile applications improves significantly, as most open-source mobile projects require test cases to be written before merging a pull request.

One thing I have found so helpful is teaching and mentoring others, it has really helped me improve my knowledge and confidence around building and working on projects from scratch. Teaching and mentoring helps me see things I wouldn't have known even if I was to just work on my own because, I will be careful just to give my students the right knowledge they need to scale through as a mobile App Engineer. It also helps improve one's ability to communicate his code implementations and why a particular functionality behaves the way it is, and what each code is doing. It also helps one to easily understand project codes written by another, I find it so easy adapting with someone else's code, because I have explored all while mentoring others

Learning they say Never ends, when you stop learning your knowledge starts dying and you become less valuable. One value that I offer to my clients and employers is my knowledge of understanding what it takes to build a business, how to run a business and what and what should be added on an app to improve the business growth, and then be able to advise the business on the best approach to go while adding features on the application. Hence as a mobile app developer you need to understand how to run a business and you can only learn some of these by learning everyday.