5

For example, it is not clear what kind of end device is used. Or which browser. Which application/service is used.

As mentioned before, a mobile phone could have other location methods than the entry point of the internet.
So you could change settings in your mini router, but the end device will override these settings.
But all this are just speculations, based on a few given information.

There is no general answer to your question. It is depending on many factors.

The industry doesn’t want people to hide their location. People want to hide their location, anyway. So both are improving their methods.
Everything solved today could be outdated tomorrow.