This isn't enough because it's not a dedicated emulator that can do nothing else. I would guess you need the inability for the hardware platform to do nothing else except be an emulator for schools to even begin to trust it.
>>dwohni+(OP)
iPads can use GraphNCalc83[1] and Apple Classroom on a teacher iPad/Mac to restrict students to the app[2]. I'm not sure if there's an android equivalent.
I still find using a touch screen much more frustrating than a calculator with physical buttons, but this is a legit alternative.