Android app that allows an admin to set a default web page for kiosk style display

We’re looking to build a full screen app that displays a default web page (changeable via an admin login). We would like the keyboard still to work when a field is selected.

The admin login will need to pop up when the app starts. Somewhere discreet and perhaps disappear from view after X number of seconds. Unless a secondary Admin app can be created to change these settings. We don’t want users to have access to change this.

To run on all screen sizes.

Has anyone built something like this before on Android? Keen to build the same for iOS if possible.

Full source code to be provided upon payment.