Fascinating for privacy and "Turn off your phone before you go to the secret location" threat models:

"What's more, even phones that are powered off or that have dead batteries can be located for "several hours" after they go dark. However, this only applies to certain handsets, including the Pixel 8 series and Pixel 9 series from Google; the phone needs specialized hardware that enables a low-power Bluetooth signal to be broadcast, even if the handset itself isn't turned on."

https://www.wired.com/story/android-find-my-device-upgrade-whats-new/