Re: what to include in a "hardware bringup image"?
It might be a bit heavy but I usually install a text editor and python-periphery (https://github.com/vsergeev/python-periphery)
(It did not know c-periphery but this is the same author)
Before having full fledged linux drivers, it allows to check devices IDs, make simple requests like get a sensor value or enable a PMIC regulator.
I'm interested in the list of packages you'll end up with... Will you share it here ?
Smile ECS - Expert technique