Advice request: tracking stolen item

[Neon22]

Someone keep stealing my friend's sculptures. I want to put a device inside that will send an alert when the device is moved and a GPS position.
The tracker board seems ideal for that but which of the various modules is ideal for being able to send a message in a random environment.
My first assumption is cellular (I assume I can add a sim card somehow) But I have also considered wifi but I'd need to tunnel through unknown networks so probably too difficult.
I am unfamiliar with the other systems.

In case it matters this is not for the continental USA but instead for Australia and New Zealand.
Oh yes and the sculptures are all metal :) so I need a short antenna, or some method to invisibly reach the 'outside' world.

What do people suggest is the best mechanism ?

[RobTuDelft]

Ill be testing with a neo-6 GPS module soon link. LoRa will be used to send the coordinates. (we will also try something like Geo-LoRa or trilateration with LoRa, but don't expect the accuracy to be anywhere near that of GNSS solutions).

The metal is probably going to block the signal in your case, but ill let you know how sensitive it is.