A&H has two different apps for the GLD. one gives full control, the other is called One Mix and does just what it’s name suggests. It allows control of one Aux Mix.
If you are only going to have one ipad “monitor desk”, just set up two custom layers with what you want them to have access to and tell ’em not to touch channel processing.
Or have them log in on the app as something other than admin, although I do not know exactly what parameters can be locked out as I haven’t had the need to that (yet!).