Reminds me of ZeroPhone project from 2017: <a href="https://www.xda-developers.com/project-zerophone-news/" rel="nofollow">https://www.xda-developers.com/project-zerophone-news/</a>, but now using a full-size Pi and a touchscreen.<p>With the current availability and prices of Raspberry Pis, you might be better off getting a PinePhone as a Linux phone.
<a href="https://skysedge.com/unsmartphones/" rel="nofollow">https://skysedge.com/unsmartphones/</a> might have a more interesting BoM to look at if one wants to do things from scratch, since a bulky pi-specific board might be too much for most