If you want physical buttons on a phone that probably happily runs graphene OS, check out the offerings from Planet Computers. I bought their Gemini PDA via an Indiegogo campaign in 2018. At the time, there were a few too many rough edges for my taste, so when it died I replaced it with a Pixel. But you are plainly more tolerant of rough edges than I am (you run GrapheneOS), and they've had at least two generations of device since then. And yes, they are phones, not just PDAs, though the original was available both with and without phone capability. Note that they don't just have buttons - they have a fairly decent small keyboard.