@agowa338 But the answer is still: it depends. What's the existing software support for the SoC and peripherals? How similar is it to already supported ones? How does the boot process look like? What resources you have available to base your research on? This all varies greatly device-to-device and if there was a guide it would have been already done.

If I were to write a guide, it would be: start with small steps on existing ports, observe others working, and you'll get there eventually.