Hi Awesome (can I call you by your first name?)
I found this thread on the Times Educational Supplement (TES) forum
$1One interesting suggestion is to use the Texas Instruments "Viewpanel" device which is meant for displaying calculator screens on an Over Head Projector but someone suggests it might work for direct viewing with a white background.
TI also make a device called the
$1 which will output the calculator display to a TV or other video device via a composite video connection (usually a yellow coloured connector on a co-ax lead).
For both these solutions you need either an adaptor cable for a student TI calculator or the "teacher" version of a TI calculator.
This doesn't help with the need for big buttons.
Another option the thread comes up with is using a locked down Ipad and a Ti-89 emulator or a
$1> But since exam boards do approve iPads (when properly locked down, obviously) for candidates with various other SENs, I can't see this would be impossible.
I can't find anything similar for Casio but here is their education contact page https://education.casio.co.uk/contact