How to display specific categories for a role or user?
There are no permissions like that for Categories. You'd have to build out that logic on your own.
Is it possible to apply css + js to the role?
Anything is possible.
What specifically are you trying to accomplish? Maybe another solution all together will work
I want to hide some categories for a role
There's still very little context in your question. Do you want to hide categories on frontend or CMS admin?
in CMS admin
For this to happen you'd have to modify the OOTB control(s) and/or code OR create a custom extension to handle what you're looking for.
Please, sign in to be able to submit a new answer.