This shouldn't be for cats only, but a general OSS GPS tracker for vehicles too (I know it can be used for that), lots of people from home-assistant community will be interested in it.
But vehicles don't need the indoor tracking, or the home base station, and when moving have nigh-unlimited battery power available.
So I imagine it depends on how much those features are adding to the price. Also, it looks like the device isn't commercially available, and with BGAs etc it's not easy to DIY either.
Yes, this is mostly a solved problem for vehicles. I have a tracker in my car that does not even connect to the electrical system. It is a somewhat bulky brick with a battery that lasts 4–6 months. Smaller units are available, trading off battery life for size.
The cost of the device is less than $100, excluding the cellular data cost.
