Semi-related: I feel like there should be an open source dumbphone project. Smartphones have a lot of bells and whistles with a large attack area but many people just want to make calls. Sure this wouldn't fix the baseband issue, but it seems the safest way to ensure isolation between personal information and potentially hostile cellular blobs is to never put the information on the device in the first place. A small, open, dialer-only yet potentially extensible cellular platform would be really welcome, I think. Maybe something like this [1] using the rpi zero as a base with some 3d printed cases, reverse engineer what you can otherwise. Replicant is a noble project, but chasing android versions, screen sizes, video codecs, proprietary hardware locks etc is an uphill battle and kind of a distraction IMHO.

[1] https://www.raspberrypi.org/blog/piphone-home-made-raspberry...

edit: typo