I use Tile, a bluetooth tracker.
This tracker use only bluetooth and the range is 60mt for the basic version of Tile.
I buyed it because i have fear to lost my backpack and when i’m walk after the bluetooth range the app send a notification with “you left your backpack” .
It’s interesting idea use flipper for this, i hate Tale because for have a notification i’have buy premium for 3,99$ at mounth or 36$ for year.
Link Tile site : https://www.thetileapp.com/en-us/