I really just want an encrypted portable linux device with a cellular modem. I don’t even care if it can SMS or VOLTE, I just need it to run a secure chat client, support Bluetooth headphones and last all day on a charge.
Then you’re in luck, because that’s something you can already have by now! Just get yourself one of the more recent-ish phones that are well supported by PostmarketOS. The things Linux phones struggle the most with these days, are the more traditional phone-things, such as text messages or calling, which may not be ready for production, as they say (although, both texts and calls have actually worked well for me as of late). But if all you want is a pocket Linux computer/PDA, and intend to carry another phone for calls and texting, that’s something you can have, for the grand price of an old, second-hand phone. I’ve been loving my (LUKS-encrypted) OnePlus 6T, and I do actually use it for calls and texts as well!
Then you’re in luck, because that’s something you can already have by now! Just get yourself one of the more recent-ish phones that are well supported by PostmarketOS. The things Linux phones struggle the most with these days, are the more traditional phone-things, such as text messages or calling, which may not be ready for production, as they say (although, both texts and calls have actually worked well for me as of late). But if all you want is a pocket Linux computer/PDA, and intend to carry another phone for calls and texting, that’s something you can have, for the grand price of an old, second-hand phone. I’ve been loving my (LUKS-encrypted) OnePlus 6T, and I do actually use it for calls and texts as well!
If all I needed was five hours worth of battery would be a great fit.
Both post-market and nix are great options if you want to run a really old phone, but neither one can last even half a day.