People with poor eyesight used to use an magnifier on top of a book or sefer. I don’t know if it was electronic or not, but I’ve also seen older people holding magnifying glasses.
A siddur is a kodosh thing, we don’t drop it on the floor. We kiss it when we close it, put it right side up, and don’t put other objects (Non seforim) on top of it.
I may be from a different generation, but I can’t see davening from an electronic device. A Tallis, a sefer Torah, a sefer they are kodosh. If this device was only for Kedusah, I think it could be counted as the above objects. (Just like a klaf became a printed book.) But the device is not only for kedusha so what does that make it? I once asked about tapes – if they need to be buried, and I was told they have no kedusha whatsoever, you can just throw them out. So how can you compare a kindle to a siddur? Where’s your Jewish heart?