I actually like the "put a case on it" approach for robustness. It lets the devices be smaller, while leaving the degree of protection and bulkiness up to individual users. Case in point, I have a very slim case on my iPhone SE and tend not to drop it, but a lot of people I know with larger phones put the 2-layer rubber + plastic Otter style cases on them because they get dropped a lot. Others have smaller or no cases, but use pop-sockets and finger loops stuck on the back to make them grippable.
Apple's phones have turned into absurdly priced luxury items, but the $800 starting price for an 11" iPad Pro feels pretty reasonable for what it is.
EDIT - admittedly the hardware is overkill for running terminal sessions, something more like a Chromebook would be a cheaper fit if the battery life and screen were of similar quality
On the iPad side of things you have options like the Rugged Book Go from Zagg: https://appleinsider.com/articles/19/01/07/ipad-ipad-pro-get...
Apple's phones have turned into absurdly priced luxury items, but the $800 starting price for an 11" iPad Pro feels pretty reasonable for what it is.
EDIT - admittedly the hardware is overkill for running terminal sessions, something more like a Chromebook would be a cheaper fit if the battery life and screen were of similar quality