From an U.S. Army perspective with 4 years and 17 days on the DoD military TDRL prior to being placed onto the DoD military PDRL in 2018, the DoD Legacy DES (LDES) PEB determines the results for military service members placed onto the TDRL. The DoD LDES PEB process while on TDRL doesn't follow the DoD IDES MEB/PEB process requirement of adapting the DoVA D-RAS provided DoVA disability rating(s) as its DoD disability rating(s).
Unfortunately, the DoD LDES PEB process shall determine the DoD disability rating(s) in accordance with 38 CFR VASRD and are not mandated to use or adapt any DoVA disability rating(s) during the DoD TDRL re-evaluation(s). So, indeed, requesting a FPEB hearing is probably your next action if you disagree with the DoD LDES PEB findings at this point in time.
In retrospect when I was on the DoD military TDRL and I requested a FPEB hearing due to disagreeing with the DoD (Army) LDES PEB findings, all available medical evidence and medical documentation was presented to the FPEB via my assigned military-provided DES attorney. The FPEB didn't ask for the completion of any additional medical examinations so I can't provide an experienced-based response to that particular inquiry. At the end of the FPEB hearing in my own situation, it was recommended that I be continued on the TDRL for another 12 months at that particular point in time. Take care!
Thus, I quite often comment that "possessing well-informed knowledge is truly a powerful equalizer!"
Best Wishes!