"We chose to base our System-on-Module (SOM) "

Holy clickbait, batman! The hard parts were done for them! All the fast signals like DDR are on the SoM, designed by real humans who understand EE. To make it all even more of a lie, their design is basically a copy of the reference base-board for the SoM.

"Boots on first attempt" well, duh! the SoM is self-contained. It boots all by itself as is... so no wonder that it boots.

No EMC results either. Making things work is 10% of the work. Passing certs on unintended emissions and making it stable is the other 150%.