Marco,

I can tell you, that shapr3d is great fun. It is not without it's idiosyncrasies and missing functionality, but modelling on an iPadpro with stylus ("pencil") is a real joy.

In terms of moi3d, it is possible to use the iPad as a second screen with duet,
so laptop screen is fully devoted to Nodeeditor while viewport is assigned to iPad.

And with another soft: Astropad, the iPad Pro can be transformed into a pseudo wacom cintiq.

Further....there is a raft of graphic programs built for iPadPro. I can't made any recommendations, as I have not made use of any to date, but I would be interested in your opinion of them.

Have a great weekend
James