Purism has a phone with the same hardware kill switches as their laptops, the Librem 5.

The issue is that it's not that good unless you value both privacy and a FOSS stack more than everything else. The SOC is not that good, the battery from what I remember is pretty bad too, and it uses Linux, and mobile Linux is still pretty underwhelming. Also people who preordered years ago are still waiting to receive theirs