So start procedure is:
Destiny2.exe -uid destiny2
"C:\Program Files (x86)\Blizzard App\Battle.net.9262\Loader64.exe" 11048 "C:\Program Files (x86)\Blizzard App\Battle.net.9262\bzrclient64.dll"
-> 11048 = Process ID after that it "normaly" should work. But I wasnt able to reproduce the whole way. Maybe someone can help and jump in. As far as I saw the Servers are still up just Launch via App is down,