Creating a PCB project around an STM32MP1xx is an quite impressive project.
Do you know that Olimex is also working on this?
https://www.olimex.com/Products/OLinuXino/STMP1/open-source-hardwareThey have also written a few times about it on their blog, I remember one of the post about long delays because of chipageddon.
https://olimex.wordpress.com/?s=stm32mp1Olimex is also very friendly towards open source / hardware and they have released quite a lot of their projects on github (older projects in eagle, newer in KiCad).
I just had a look at
https://github.com/OLIMEX/STMP1-OLinuXino and I was a bit surprised that the project has not been updated for 3 years. The schematic looks fairly complete, and footprints are placed on the PCB, but not much of the routing is done. I'm guessing this is not intentionally but it just slipped in between the cracks somehow.
Olimex also has a forum section dedicated to this processor. It may be a useful place to look what others are doing with it.