The hardware and software, in any device, should not be so inextricably linked as to prevent the hardware from working at all without the software. Regardless of whether we are taking about iPhones, computers, cars, or farm equipment.
The idea that a CPU is going to come out of reset and start executing instructions that you provide at the reset vector is thirty years out of date.
ref. https://doc.coreboot.org/northbridge/intel/haswell/mrc.bin.h...
... plus Intel's microcode.
Looking at Linux and all the devices it powers (including most of the internet infrastructure) - it would seem that it is possible to do pretty good security on very open software that's as separate from the hardware as can be.
Don’t conflate user freedom with just…being salty that not every product is for you.