2) battery life will depend on which OS you use, peripherals, software duty cycle etc. It's a hacker device, don't expect it to work without putting in the effort to tune/tweak it.
Would you like some help with that?
I was only planning to add sixel support, but I could prepare you a simple configuration to use a cheap 4G module like the Quectel EC25 () at least for sending/receiving SMS, and maybe acting as an access point.
() Other options would also be possible, like Qualcomm SDX55 and SDX62/SDX65 for 5G, but the Quectel has more community support since it's also used on the linphone
Been working on a pi400 eink solar powered cyberdeck but haven’t done anything with cell connection yet.
So could follow long for that and for the blackberry.
Using an internal Qualcomm SDX module, I've already got both 4G and 5G working great on my Thinkpad with just a few AT commands, so I don't foresee any practical difficulty except maybe getting MLC03 submmWave antennas (I can't find any, so I stick to B71 on 5G)