You seem to be using “focused”, “highlighted”, and “toggled on” interchangeably, but in standard uGUI abstractions those are all distinct things. I am confused about precisely how you are trying to map the standard abstractions to your desired functionality.
I don’t think Unity provides any callbacks for when a button or toggle is selected or highlighted, so if you want to run code when those things happen, you’ll either need to use polling (check every frame for changes) or somehow detect the preconditions that cause them to happen. You can check what object is currently selected via EventSystem.current.currentSelectedGameObject (in namespace UnityEngine.EventSystems).
(b) My best guess is that the click event is being “intercepted” by another object. Typically, if an object has NO handler for a particular UI event (such as pointerEnter, or click), and it receives such an event, it passes that event up the object hierarchy until it finds an object with a handler. But if an object has AT LEAST ONE handler for that specific event, then it will handle it “locally” and the parent will never hear about it. So, for example, if you have a child with a click handler, that can prevent you from detecting clicks that fall within that child.
But there’s lots of subtle errors that could theoretically cause you to fail to receive events. For instance, maybe you implemented the OnPointerClick method, but failed to update your class declaration to specify that you were implementing IPointerClickHandler, so Unity doesn’t know to call it.
Often it’s helpful to test out your script in a very simple scenario (one object, no unnecessary other components) and then add complications in gradually until you figure out which complication is breaking things.
(c) Remember that keyboard selection is NOT going to trigger a pointerEnter event, so if you are relying on that to set the toggle to “on”, then it’s not going to turn on even if keyboard navigation is working the way it’s supposed to.
Make sure that your Input is configured properly. The Event System in your scene has fields that define the specific inputs that it looks for to control keyboard navigation (by default: Horizontal, Vertical, Submit, and Cancel). Check your input manager to ensure that the keyboard buttons you are pressing are actually bound to those inputs.
If you select the Event System object while in playmode, it will display some debug information, including what object is currently “selected”. I’ve recently had some headaches where if NO object is currently “selected”, then keyboard navigation cannot seem to “get started” because it doesn’t know where to start from, so you might need to do something to make sure SOME object is selected in the first place. (For testing purposes: I usually press the mouse down on a button, drag the mouse away from the button while still holding down, and then release; this results in the button being selected but not clicked.)
Again, you might find it helpful to test in a simpler environment to make sure the basics are working before you test in your weird custom set-up.