The Jolla Tablet, the Jolla C/Aqua Fish and the Turing Phone all only have less than 2,5GB system memory (see https://together.jolla.com/question/154944/ or https://together.jolla.com/question/153509/ with no solution and a bricked phone). 2GB of this is immediately filled, and system updates require 500MB free memory. Ergo, installing system updates is impossible.
How can this be solved? Why is the system partition not at least twice the size? Whose fault is this?