I believe GPS units consume energy more than the latest crop of trackers. There are various ones such as the one called Tile. I have experience with Apple Airtags plus one compatible Airtag device. They connect to a nearby iphone, and they secretly tell the iphone (which may belong to a total stranger passing by your Airtag) the location where the Airtag and the iphone met. So if the world gets saturated with iphones, your item will always have its location be known.

One problem with putting anything that uses radio for location is that bicycles are made of metal, and metal attenuates signals. You could hide the tracker inside your frame, but that would make it less useful. When put it in a place that's useful for tracking, you also place it where a thief can see it, remove it, or disable it.

Another problem with these is what to do when you know where your bike is. Suppose you meet your bike with a person on it. Do you assault the person? Detain him and call the police? Knowing where it is, that's a nice thing, even if you're not going to confront your thief, but what is next?

I have an Airtag on my key ring and a wallet card thingy in my wallet. Wouldn't it be nice if they could make one small enough to fit on a pair of eyeglasses? These things are useful to me because I can't find my keys in my home, or I leave it at home and can confirm that it is safe at home. This way I don't have to replace my drivers license and credit cards or change my locks.