Here is some information I found at https://www.thebalancecareers.com/transfering-from...
There Is No Simple Transfer Process.
It actually can take months to process. A reservist or guard member must first be released from their reserve status and basically apply to join the active duty ranks. That means finding a recruiter to assist you with the processing into the military (active). The Guards, Reserves, and Active Duty components are all different. With very few exceptions (mostly for medical professionals), one cannot simply transfer from the Reserves/Guard to active duty. One must get an approved discharge from the Reserve/Guard component and then separately process for enlistment (or commission) for an active duty service.
Exception: Some Army Reserve and Army National Guard soldiers who are currently activated can apply for direct transfer to active duty.
However, one may apply to the Reserves and/or National Guard for a "conditional release." Basically, a "conditional release" says that the Reserve Component. or National Guard agrees to release you from the remainder of your commitment if you are accepted for enlistment or appointment to an active duty service component. Regardless, the official process is still long.