Detecting child's phone is "in use"

[ckelwin]

Is your feature request related to a problem? Please describe.
Should we add a way to detect if the child phone is "in use", e.g. screen is on (not sure if this is possible). And possibly even which app is on the foreground? Or else, just from the parent app, wouldn't know if the child is actively using the phone or phone has the screen off-ed already. imagine, getting a notification "go to bed" when the kid is already in bed.

Describe the solution you'd like

On the 'parent page', the child icon can be 'highlighted' (see screenshot below) when the child's phone is 'in use'.

In the 'child page', there can also be an icon/image (with text = In use), beside the battery icon.

@JordyHers for your consideration. Do update this issue as you see fit. I'd like to work on this. Please assign it to me once you're ready. Thank you.

[JordyHers]

@ckelwin the only thing is that I have marked it as v3.0.0 milestone