Why don't think about zerophone? [[https://wiki.zerophone.org/index.php/Main_Page]]
Their attempt to build free hardware is very interesting, and with some modifications (touchscreen instead of little screen + keyboard) maybe it can work with replicant?
RE: Zerophone - Added by Kurtis Hanna 4 months ago
We have recently been trying to focus exclusively on devices that have free software bootloaders that require no proprietary binary blobs.
Here's someone who tried to put u-boot on the Rasberry Pi Zero: https://ktln2.org/2018/10/28/u-boot-rpi0/
It seems as though the stage 2 bootloader is a binary blob called 'bootcode.bin'. Unless this blob is able to be removed, we likely won't be interested in this device as a potential target for Replicant.