Those in this thread recommending Chromebooks are missing a big part of the equation. You don't need to be able to read to use an iOS device. Chromebooks are much more reliant on the user knowing the written word to interact with the device (unless their is some elementary school mode that I am unaware of). As long as you can recognize icons, you can interact with an iOS device and switch between apps.
I’m curious how you’re applying that to kindergartners.
I started using computers around age 4. I couldn’t read for shit. My parents didn’t withhold technology because I couldn’t read the manual. I’m thankful for that, as now I’m a software engineer and love it.