If you come from a background of DSA, SR3 etc. you are accustomed to very fine-grained, small steps character improvement.
If you look at Traveller (almost no character improvement at all), you know how it is to play characters without any change in their stats at all.
The 2d20 system comes in a lot of variants, some very fine-grained like Mutant Chronicles or Infinity RPG, some more in the mid-range like Conan, and the more recent ones in the more coarse-grained range like Dishonored, Star Trek Adventures and - even more coarse grained - Dune 2d20.
Dune 2d20 characters have only very few “moving parts” and so you will probably not see much in the way of small, but frequent, steps of development like in DSA or SR3.
The recent 2d20-based games have a lot of mechanics inspired from Fate and some from Cortex Plus (Smallville). Those are very coarse grained systems, less focussed on gaining more abilities and more about CHANGE your character goes through.
And that part you see already in the Dune preview. If you challenge your Belief statement you get to change your character’s outlook on the world - but the character does not get “more powerful” or so, the focus of the character’s abilities only shifts.
This is similar to what you find in Star Trek Adventures, where gaining an actual increase in abilities (Attributes, Disciplines, Talents) is a VERY rare occurrence, the culmination of a whole “season” of episodes played with this character gaining often spotlight.
So, for Dune, I wouldn’t expect much in regard of gaining or improving personal character competency, but more in the direction of shifting the focus, shifting alliances, relationships, moral values, beliefs, etc. - more shift, less increase. In that regard that would be quite the opposite of what you know from DSA or SR3.