That won't really work because the trackers themselves need other people's phones to work so they basically have to be integrated with some large phone vendor's or phone OS vendor's infrastructure.
I'm not looking for a Tile-like network. Most of these cheap devices seem to work off of just letting you know when you are disconnecting from their Bluetooth as far as I know.
Yeah I know that's part of the reason I'm looking for an open source alternative. Tile does more than that when you have a membership but I don't need a huge suite of features