I turn the pages on my Nook with its touchscreen function exclusively, not bothered with the physical buttons. This is how I hold it:
https://www.mobileread.com/forums/att...4&d=1311175092 . If in my left hand, I do the same index finger/thumb thing.
I usually hold it in one hand like it is a physical novel, with my index finger perched at the top corner. If in my right hand, my thumb would then be used to either touch the right side of screen to move forward or swipe to the left to move backwards. Similarly, when I use my left hand, my thumb would swipe to the right to move forward and touch the left side of screen to move backwards.
Maybe you can go into B&N to see if you can get a comfortable grip? If you want to use the physical buttons, they are there. I have not used mine yet to have them 'seasoned' and soft to the touch, but they are not that difficult to depress.
One of the negatives is it does not have backlit screen. On the other hand, I appreciate the reduction in eyestrain. Plus a booklight would compensate for that without compromising on battery life.
Alternatively, if there are other readers whose functions you like but you do not feel comfortable gripping onto, there are numerous covers on the market that will add that bulk without too much weight.