Do you need a stem degree in order to recieve a commission for STO ? I only ask because the regaf is very specific with handing out commissioning slots to stems first. (I am aware of the phase 1 & 2 process.)
The military commission is either a Rated or Nonrated Line Officer commission or a Professional Commission (Physician, Nurse, Lawyer, Clergy). There is no such commission for STO or CRO other than the requirement to hold a nonrated line officer commission.
There is no specific type or required type or desired type of baccalaureate required to be classified into the CRO and STO utilization fields. You can have any basket weaving or STEM baccalaureate degree.