Looking for some resources to advance my android knowledge, I'm already an android developer but want to learn more I.e to become a lead etc

The difference between a good senior and a lead is less about technical skill and more about management. Coaching, ensuring your team members progress, budgeting, recruiting, commuting to deadlines.

These are the things that make a good lead. A strong senior should be having regular debates with their lead because they're both usually equally technically equipped; it's just that one is ready to lead and one isn't!

Agreed!