We got more secure AirTag holders for the cats and changed the batteries because it’s been a year. Naturally Bun here thought she’d been subjected to war crimes.
We chose AirTags because they only require this annual battery change. The range is limited (about 10m) but they will ping off any Apple devices with the “find my” app enabled - which in practice gives them endless range at least insofar as getting close enough for fine tracking.
Another thing to be aware of is that fine tracking is only available on iPhone 11 and up. @withoutaleaf’s 12 does it while my SE only allows me to activate the sound which I can then track down by ear. Still it has been a good solution so far and would certainly have prevented the Boi being lost for three weeks last year.