>>1085689 (OP)
>what's the state of good non-proprietary portable technology?
it is in good shape given that there is some interest from the public, and the prices are low for some convenient devices i.e. räspberry pï among others.
>phones
99,9% are propietary garbage, 99,99% of them have or could have hidden blobs or shit, thus they are mostly not completely to be trusted.
there are good ones but one simple solution to avoid surveillance nightmare is to simply don't have phones, or have the old burner type which you can disconnect at any moment (large discussion not for this thread..)
For your information, rpïs also have ((( binary blobs ))) at boot level, thus is also not 100% secure..
But going back to your question: in my humble opinion, something akin to this could work for a semi-portable solution (not as slim but still easily movable)
-5" touchscreen
-connected to a rpï (preferrably 3b+) or banana pi or similar
-portable or small keyboard
-wifi dongle for connectivity (if needed)
-it would be very helpful to have a sort of custom mini keyboard / macros for quick tasks, like enabling / disabling touchscreen, consulting gps*, take photos quickly, and so on..
>battery
use 2x18650 and charger to charge it like a phone, would last this way about 5 hours of usage or 10 hours idle ; more than necessary in my opinion. Or go robust with 4 x 18650 , build it with as much as you need.
Feel free to give your insights, anons, but this is my solid and honest response given that i myself did my investigation and want to escape the techno dystopia we are immersed into at the moment.
*openstreetmap, not ((( google ))) or other propietary shit