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.

This isn't that. This is like google maps indoors for walking around malls and is no where near accurate for anything else.

For inventory you could use decawave, but it would be pricey.

That's what they claim on their website, but you are right, I think Indoor Positioning System would be a better description of what Anyplace offers. <2m accuracy is good enough for me though, just wondering if there are any alternatives. And thanks for the Decawave suggestion, good to be aware of it but it is waaay too pricey as you mentioned