I thought I'd reply here. The touchscreen issue is a bit disappointing, considering its 2019 and we don't have cheap sunlight readable options.I think the Pi has enough horsepower to do everything. However at present AOG will not run on the pi. It depends on some x86 binary dlls, as well as winforms. If a Qt port is completed, then it would definitely run on the pi. And yes it could probably do all the things we're using arduino for as well. But then you have the problem of the touch screen, as well as power management issues. Definitely doable and it's interesting to me.
I'm still looking through those options and trying to get a feel for prices but it sounds like those bonded touch sunlight units is the way to go.