Gearbreakers by Zoe Hana Mikuta

The shadow of Godolia’s tyrannical rule is spreading, aided by their giant mechanized weapons known as Windups. War and oppression are everyday constants for the people of the Badlands, who live under the thumb of their cruel Godolia overlords.

Eris Shindanai is a brash young rebel who specializes in taking down Windups from the inside. When one of her missions goes awry, Eris meets Sona Steelcrest, a cybernetically enhanced Windup pilot. At first Eris sees Sona as her mortal enemy, but Sona has a secret: She has intentionally infiltrated the Windup program to destroy Godolia from within. As the clock ticks down to their deadliest mission yet, Eris and Sona grow closer…