holding a tablet in my right hand... Tapping the left side of the screen is near on impossible
What are you doing with your left hand? 😏
I normally read lying on my bed so just press the left hand side of the screen. If I do go one handed I hold with my left hand and use the thumb to tap.
I've just checked the 4 different readers I've got:
The function @WMD
mentioned I nice, especially on mobile, but you still need to tap or swipe the same as full screen.
Shounen Jump app
You can switch to vertical where you can swipe up, but I don't think you can buy books. Just read chapters as they are released.
You can use the volume buttons, but only in a feature called Bubble Zoom which scrolls through the speach bubbles and other text. Again useful on phones, but probably would be annoying on tablet where you can read them easily anyway.
The best of the bunch you can switch sides and make the zones bigger or smaller:
You also get the option to use the volume buttons.