I want to fit a mixed model to determine a treatment's effect on a circular response variable (the variable is an angle measured in radians). I want to know how treatment changes both the mu (mean) and kappa (concentration) of my response.

Does bpnr output provide estimates for how my predictors drive both mu and kappa? Is that what components I and II are?

If not, are there any packages that allow for this? Maybe brms?