I'm trying to implement Android device administration on a range of company-owned devices. The network these devices will be on does not have an internet connection - It will only have Wi-Fi connection to the enterprise network.
I have the device working with a policy controller, all hard-coded into the app loaded via Android Studio.
My next step is creating an Enterprise Mobility Management (EMM) console, but the documentation seems to explain that it's cloud-based and require Google accounts. Is there a way to implement this functionality on an offline secure network without Google accounts?
Yes, there is a way to implement device management functionality on an offline network.
Headwind MDM, the project I am working on, is a self hosted mobile device management solution which can manage Android devices without Internet connection (using Wi-Fi or private APN in mobile networks). Also, it is open source so you can adjust the code for your needs.
The only exception is that you may need Internet connection during the initial setup of your Android devices, because some models require access to Google servers when installing the device owner application (to initialize Google Mobile Services).