[okanat]

If you would like to see an actually "interesting" boot, I recommend checking out how Raspberry Pi's boot.

It is a unique monstrosity that boots from the video / GPU core instead of one of the ARM cores. It has an arcane undocumented architecture.

[megous]

When I realized that, after buying my first Rpi (2B), that was the last Rpi I ever bought. :)

Thankfully, pretty much everyone else just uses U-Boot.