@mcc Np, just ask. The Xperia 1/5 III is a new model.
I didn't found any problem regarding DRM in the Xperia 1/5.
The Xperia 1/5 no matter which version do share the same base (also called board).
Porting the Xperia 1 or 5 means also porting the other except extra variants of packages.
I don't have hardware to port the Xperia 1/5 III.
But if anyone wants to start porting those I can help and provide the project infrastructure
to do so.