I have work with networks for a better part of 30 years and honestly also cannot understand a use case for this.
What exactly are you trying to share and to what hardware? without a service provider that will provide you a LAN let alone a WAN you can’t do what you want.
Here is an example. If you have an iPhone, please set it in airplane mode and try to enable it as a hotspot. You can’t. Your vehicle is in the same boat. If you’re not connected to a service provider, it will not act as a hotspot provided that you have the capabilities to be a hotspot. I do not Have 4g capabilities in my ST as it did not come with the option. Nor do I wish I had one.
When I get in my car, I turn the hotspot on on my phone, which creates a LAN, and if you need assistance, you can visit
https://cricket-wireless.pissedconsumer.com/customer-service.html, for anyone that is in the car including the ST itself so it can upload updates.
I know you don’t want a hotspot bu