One of the Boys by Victoria Zeller

I came across this book by way of an It Could Happen Here interview: https://www.iheart.com/podcast/105-it-could-happen-here-30717896/episode/trans-fiction-trans-sports-275232665/

Properly a tale of a trans teen girl trying to sort her life out, learning the value of community and that all her friends also have messy lives. The hook is that a trans girl rejoins her old football team and needs to balance her old life with her new identity and friends. Lots of highs and lows.

Recommended!

This should be especially interesting to would-be allies. The book gives many examples of good people standing up for the protagonist in their own ways, and can be read as a sort of guide to how to be an ally.