Recs if you like Hard Reboot...

Speculative (sci-fi, fantasy, horror etc.) novellas less than 200 pages long that are either standalone or read like a standalone story

With bone-piercing bolts and mechanically enhanced strength, meat and metal convene in these books as our iron-bound protagonists engage in the next step in the evolution of battle.

This list includes novels, short stories, and mangas whose central plot features Powered Armor (including magically enhanced armor), Mechs, or more generally protagonists who have undergone any sort of marrying of metal and flesh.

Recommendations welcome! General rule: they have to battle.