First for clarification: Doing residency in PA does not require an unlimited medical license, it simply requires a training license, and as such PA's requirements for an unlimited license for a DO doesn't really matter unless your residency requires an unlimited license prior to graduation from the program, you plan to moonlight, or you plan to stay in the state for work after you graduate.
Licensure is based on your state medical boards, there is no AOA or ACGME licensure. Some states have separate MD and DO state medical boards. PA is one of them, and the PA osteopathic medical board is further one of only 2 state osteopathic boards (FL is the other) that currently, and as far as I have heard will consistently, require an AOA-equivalent intern year in order to get unlimited medical licensure as a DO.
As of right now, there are 3 ways to achieve this:
1) Attend an intern year with "Osteopathic focus" prior to starting your ACGME-only residency. This means you'll have 2 intern years, which is stupid and you shouldn't do it.
2) Attend an ACGME residency program with "Osteopathic focus" and as such the first year should (as far as I have understood the changes with the merger) qualify as an AOA-equivalent intern year.
3) Complete an application for Resolution 42 in order have your ACGME intern year recognized as "AOA-equivalent".
The third option is the process/link that
@samac posted. This can be fulfilled by completing the application online, completing some type of osteopathic thing (i.e. writing an osteopathic research paper, giving a presentation at your residency grand rounds about OPP, or attending an osteopathic conference to get 8 hours of AOA CME-1A credits), and getting a letter from your PD with a description of your intern year and stating that you satisfactorily completed it. From what I hear, this process is usually almost always approved assuming all requirements are fulfilled.
I actually attended my 8 hrs (and literally no more) DO conference in early March just before things shut down for the pandemic, and completely forgot that I didn't submit that letter from my PD yet, so thanks for reminding me. I'll let you know if I have any issues with this process, but if you never hear from me, assume its all straightforward like I described.