Android app - serial console UI for control and monitoring -- 2

I have a project that involves configuring a heating appliance through the local USB serial console. Normally the product uses cellular connectivity, however local configuration and monitoring may be required when connection is poor. I am looking for a simple offline Android app that can be used by engineers in the field.

You will need to design and develop mobile frontend and find a suitable USB serial library to communicate with the appliance. We have some simple wireframes and examples of console commands. A hardware emulator will be provided that emulates behaviour of the appliance for the purpose of testing. A web app is already in place, to get some ideas from. The build process needs to be fully documented so that we can reproduce it reliably.

The UI will essentially consist of two tabs - Settings and Sensors. Settings will be configured with +/- buttons or sliders and sent to hardware with Send button. Sensors page will display several numeric values and have a Refresh button. App settings will be saved locally on the phone. Deployment through apk, no web store submission.