Your per unit cost of item tracked would be quite high, but there's a version of the client of https://www.internalpositioning.com/ that you can run on ESP32 boards. You'd need to figure out a power solution for the device too.

I've had success putting 18650 cells and then 3d printing cases for these: https://www.amazon.com/Makerfocus-Battery-Shield-Raspberry-A... Battery last long enough for peronal tracking around my house, but likely wouldn't be long enough to track the thing for multiple days in a row without a recharge.