I found out that many of the arcpy.mp commands works only when you use the current aprx and running the code in a tool or python winodw.
For example SetExtent or updating the layer metadata.
Is that a bug, known limitation or documented feature?
After the long read, I suspect it is a work in progress. There are comments about what should and shouldn't be done as well as a lot of the examples have been placed outside the help topics in github or the code sharing site
Also, you can have a stroll through
to get a sense of what is there... the folder is getting bigger over time
"current" ... seems to be the current preferred access to CIM,
True, I find it hard sometimes to track down whether "stuff" is available or not, for example, setExtent and getExtent are only found in the Camera class accessible via the Map class and metadata seems to be class specific