Worth mentioning is that OpenMandriva is a small group of all part-time, unpaid, volunteers.
While OpenMandriva is a direct descendant of Mandriva there is not a goal to keep everything the same as it was in 2012 and earlier. Things in Linux change to fast and to much for that to be practical.
@AngryPenguin makes some good points in his post.
urpmi and drakx tools were dropped with release of OMLx 4.0 in 2019. Both were dropped because of code developers considered to old and out of date to maintain.
OpenMandriva package management is unique to OpenMandriva.
It may be helpful to have some documentation to refer to when you have technical problems (like how to use dnf):
OpenMandriva Forum Resources (User how to’s and tips)
Sometimes user can get quicker answers to questions on OpenMandriva IRC.
Thanks for the kind words.
I do not know why OM developers do user and group id’s this way so I leave that for one of them to explain. This is a good question to ask at OpenMandriva IRC. Perhaps you could install OMLx with a “extra” user and after install create the user you want with the id #'s you want.