Back to the question,
...and I am wondering, "Is it possible to flash a ryzen... .
Correct. Understand "Flash" came from "flash memory", a type of
erasable programmable read-only memory (EEPROM) device. The "flash" term came about by the developer of flash memory because the high energy UV light used to erase such EEPROM devices reminded him of the flash of camera's flash.
CPUs are programmable devices, not
reprogrammable. That is, their programming cannot be erased then programed again with different code like an EEPROM can. Existing programmed features can often be enabled and disabled, but not changed.
Microcode is loaded (flashed) into pretty much every consumer CPU from the bios on every boot.
Sorry, but that is not true. Flashing implies
reprogramming the code in a device. That does not happen at boot. All the BIOS does is apply user defined allowed options (set in the BIOS Setup Menu) to the defaults already coded (burned) into the firmware of the chipset/BIOS. Those changes are stored in the CMOS device. And CMOS devices are not "flashed". Data is "saved" in the CMOS memory device in a very similar way as data is saved in regular DDR3 and DDR4 RAM. If you remove power from RAM or the CMOS device, the data is lost. If you remove power from the EEPROM, the data is retained.
See
volatile vs non-volatile memory.
Once the hardware boots, the OS boots and the code from those processes are "loaded" (not "flashed") into the CPU and system RAM.
"Loading code" is totally different from "flashing code" and should not be confused.
