"Becoming better" points to the question of what is a good tech leader and how you can evaluate yourself as you make progress on this path. In my experience and according to Google's research in this area (
https://rework.withgoogle.com/guides/managers-identify-what-...), there are specific traits to cultivate:
1. Is a good coach / Supports career discussions and discusses performance
"Leader As Coach: Strategies for Coaching & Developing Others" by Mary Dee Hicks and David Peterson. An in-depth, very practical manual on how to coach your reports according to their specific needs and personalities.
"Crucial Conversations: Tools for Talking When Stakes Are High" by Kerry Patterson et al. Helps you prepare and approach difficult conversations with empathy. Especially useful for performance conversations.
2. Creates an inclusive team environment, showing concern for success and well-being
"The Five Dysfunctions of a Team: A Leadership Fable" by Patrick Lencioni. If there is one book to read about team dynamics, this is the one.
"First, Break All the Rules" by Marcus Buckingham. Slightly more general than the 5 dysfunctions, but with a lot of good content about psychological safety and what makes team work.
3. Has a clear vision & strategy / is a good communicator
"High output management" by Andy Grove. Probably the most famous book on this list. It gives you a good introduction to setting goals, communicating about your team's work inwards and outwards. It also features more "system thinking" than the other books - how everything fits together as organizations scale, which is useful for developing vision and strategy.
I'd also recommend reading biographies and memoirs of famous leaders (e.g. Churchill, Marcus Aurelius). Strategic thinking can be easier to learn through examples and pattern recognition than through abstract / self-help books.
4. Is productive and results-oriented / has key technical skills to advise the team
A lot of new managers over-index on the people management side of the job and forget about the key responsibility of a technical leader: choosing a direction, leading others in this direction and delivering results.
"Accelerate: The Science of Lean Software and DevOps: Building and Scaling High Performing Technology Organizations" by Nicole Forsgren et al. One of the most recent, well-researched books into how to measure the productivity and quality of software teams.
"The Art of Scalability: Scalable Web Architecture, Processes, and Organizations for the Modern Enterprise" by Martin Abbott et al. This book uniquely blends the technical, organizational and people management aspects of technical leadership.