To be honest, I think I would like owning the hardware, but could not deal with the software.
There seem to be a few companies making "feature phones" again for various reasons, but none of them are investing in the software.
KaiOS, running on some Nokia devices, is very very slow for the hardware. Nokia's S30+ operating system is dated and very crap. Other feature phones on the market seem to use Android or another bad proprietary OS.