The wonderful things about good AT specialists is their ability to adapt to unusual situations. I wonder if MY AT PERSON could help you. I mean what's the difference between her zoooming in across the state in the US and zooming to the other side of the world? PM if interested and I will send her contact info. At the very least she may have professional contacts to point you to where you are.
DD can't use just one device. She carries a backpack as big as she is because different tasks require things that are only found on one or the other. She shares most work through Google. But then again she has 11 diagnoses - issues with info going in as well as coming out. Your kids may not be as complex. She has an external keyboard for her iPad so you don't have to be limited to a laptop for that feature.
Math is done 1-1 with a special ed math specialist. DD prefers to work with pencil and paper although she has been introduced to some math apps. I know she used one for plotting a graph for a lab report. She has literally no automaticity in math but gets the higher level concepts. It's so individualized for her I'm not sure how much I can help in that regard.
