Once upon a time, Bill Cunningham <bill.cu1234@gmail.com> said:

...

There's no magic reserved space outside partitions that is used for
booting anymore.  The firmware finds the device, reads the partition
table to find the correct partition, mounts that partition and reads the
configured executables from it.

OK I see, thanks exactly what I was asking. So if for some reason you wanted to save boot code, I guess, you would save partitions and files?

Bill