What is the "best" receipe for building a NED from that YANG model please ? Should I still use "pionner" in 5.2 ?
The easiest way is to use the "ncs-make-package" script that is part of every NSO release.
$ ncs-make-package --netconf-ned --build /path/to/yangfiles my_netconf_ned
In addition to ned packages, you can make skeletons of java/python packages, template based packages etc.
See "ncs-make-package --help" for all the possible options.
/Ram