In order to start deploying 4G/5G everywhere, some prerequisites must be considered.
A typical project with thousands of nodes costs a few million euros.
It is better to start a project after some real need has been identified: in car parks, inside building, factories, etc. In some countries, 4G/5G is already everywhere. In some other countries, many people are opposed to radio networks. A project will fail in both cases.
In some regions, unlicensed frequencies can be used. In other regions, it is necessary to obtain a commercial or an experimental license.
If we want to reuse existing SIM cards and phone numbers, it is necessary also to find a telecom company with an S1 interface. Without S1 access to a core network, a local core network can be used for data-only service.