Yeah, it’d be a live monitoring footprint limited to, say, wherever you have/bring a personal device plus maybe wherever there’s a wifi network it knows. But you’d be able to see where the tag was when it last pinged you, so you could return to that location to search for it and get a more accurate location fix.
The only case my example doesn’t cover is if a third party moves the tag away from your typical footprint and networks.
Yes: https://prosody.im/doc/turn
Further notes on implementing calling with XMPP: https://gist.github.com/iNPUTmice/a28c438d9bbf3f4a3d4c663ffaa224d9
…seems like things may have stagnated around group calling; for now probably need to consider something more video conferencing specific like jitsi or bigbluebutton.