Having just changed out the battery on my trusty Note 20 Ultra yesterday, this made me smile as I imagined a thief evenly applying heat to the back edges of the phone, carefully prying the phone open with suction cups and a series of plastic picks, gently dislodging six fragile micro-connectors, removing 11 different nano-sized screws, removing the wireless charging antenna, peeling back layers of ribbon connectors, removing the speaker module, dripping solvent into the battery compartment and then waiting ten minutes for it to soften the battery glue so they can start prying the battery out.
Maybe somewhere during that painstakingly onerous process, they'll pause and ponder their life choices. I know I certainly did! :-).
I think the only quick action that doesn't require you to unlock the device is the flashlight.
Of course the thief can still forcibly shutdown the phone or open it and remove the battery.