(for various reasons I needed to join a mismatched pair of 18v drill and battery, annoyed at how much fun it was)
I thought there was communication between the drill and battery that would keep this from working.
Mostly only the charger cares. A tool often only has power contacts. Something “smarter” like a camera with battery life gauges in the menu etc will most likely want to talk to the battery.
But if the company thinks the extra cost in manufacture is worth it, they’ll probably choose evil.
Some brands have the BMS in the tool, others have the BMS in the battery. When it’s the latter it’s fine to mix and match.
That comment might be helpful: https://lemmy.world/comment/11473650