As a consumer, all I want if a very minimal "phone", with wifi, touch screen, battery, but no 4g or mobile networking, and linux on it. Just the cheapest, smallest, wifi, battery-powered, touchscreen LCD device that could exist that can run executables.
People are going to say "but just buy a cheap phone", but I cannot really run custom software on those, I can't expect to install a custom system image, and generally even cheap phones CPU SOC are way way too powerful. Open source phones are generally crazy expensive and very powerful, and I am not going to buy those.
With the range of hardware that exist out there, I think such device could cost about 60 euros, and it would be more interesting than a RPI.
The RPI is an amazing product, but it lacks an all integrated consumer device with an actual screen and battery. Of course I can already build one with a compute module etc, but it's not really portable and not designed around a flat battery.