Android and mobile development as a whole is something I'm very interested in. For example, I see the Taro Android app, and it's pretty smooth and performant while being built quickly. What can I do to get to this level?
Just build Android apps!
Android is literally one of the most accessible platforms in all of software, which is one of the reasons why I love it so much. It's just $25 to publish as many apps as you want, and you get all this incredible infra from Google Play for free. After doing iOS for a while now due to Taro, I can confidently say that the Android developer ecosystem is far superior.
You can read a book here and there and do a tutorial if you want, but when it comes to Android, heavily bias towards just building. That's how I started off my Android journey - I just wanted to deploy some fun apps onto my personal Android phone, so I just downloaded Android Studio, did the developer.android "Hello World" tutorial and from there, I just started Googling everything to build my first app: Borderlands 2 Soundboard (it got ~14,500 downloads before it got taken down).
Another thing that makes Android such an accessible platform is it's one of the most StackOverflow-friendly tech stacks. Google will deprecate things, but they won't rip it out and they go to great lengths to make sure old code doesn't break - If you find an Android Java code sample from 2011, it probably still works!
I talk in-depth about my experience publishing ~30 apps for fun with 3 million+ users combined here:
For folks looking for more "hand-holdey" resources, I recommend these excellent tutorials:
From the above tutorials, I don't think any more are needed - Doing more than these will put you in tutorial hell. They give you 80%+ of the core concepts; now it's up to you to play around with them and sharpen your understanding.
After the more curated learning, fill in your knowledge gaps with the following:
Lastly, here's some very tactical tips:
As a junior engineer, your goal is to learn the most basic and core concepts and get stuff to work. Android is a very mature framework at this point with many different APIs and frameworks, so be careful and avoid getting sucked into the very complex and modern material. Just build stuff.