But there are a great series of tutorials from Lupyuen where he gets Apache Nuttx running on the PP. He fills in a lot of the missing documentation and magic smoke details.
For example: https://lupyuen.org/articles/dsi#initialise-lcd-controller
I'm currently following the same reverse engineering process, but using Zig. The A64 is quite fun to play with, but I think the hardware might be better suited as a feature phone vs full linux. I'll let you know in 10 years time hehe.