Getting the Fi series 3. GPS is the best and this is smaller and more discreet than the others, with good ratings:
https://shop.tryfi.com/products/smart-collar-v3?collarType=standard&color=pink&size=medium&srsltid=AfmBOooUwRZBjrRS4LD6cca-YWKsu6rgXAt5BeivlXCQsRiQHlaolTqc
Putting it on an Atlas Lifetime Pro collar with my phone number stitched on like it says "ATLAS" in this pic:
Unfortunately the stitching isn't compatable with the buckles in the above photo, so getting the Fi snap to clip the buckles around the collar:
An apple Airtag would be a lot cheaper without a subscription fee, and there's a lot of collars that will carry them (some discreet), but it has to be in 75' or so of an Apple device to report its location.