"offline" LoRaWan network

At my work, we build wireless networks for industrial customers to support device telemetry and control. Many of these customers have policies that prevent pretty much any sort of interaction between their device networks and the outside world. I’m fairly inexperienced with the guts of LoRaWan back-end at this point. Are all the pieces necessary to operate a network, authenticate new devices, etc, available as software that can run “on premises” and not in any remote cloud? In other words, can a functional LoRaWan network be built that has no internet connection of any kind?

Yes, there are no shortage of private or airspaced/disconnected LoRaWAN networks, ChirpStack or otherwise.

Excluding hardware gateways, are the software components of Chirpstack sufficient to build one, or are additional components required from elsewhere, and if so, would you have any recommendations on what and from where? (We presently build networks on other technologies, but I am investigating building an internal technology demonstration for others where I work to consider as an example of what we might in the future do commercially)

Ample documentation is available here:

https://www.chirpstack.io/docs/

Topics include configuration, deployment, and building from source (optional).