Appears to me the holster is a standard WWII P..08 luger holster that could use some tender love and care with a good leather preservative. You are fortunate to have such a piece of WWII history. There should be a makers name, a two numeral date stamp and P.08 stamp on the back. The name on the inside of the flap could be "Schmidt" or something close to it, hard to tell tho.
There is a manufacturer mark, year,and waffenamp n the rear of the holster, but they are faint. It's cdg 42. I was hoping a person familiar with German cursive writing would have insight into the ink markings on the flap.
Very common for names of "owners" both German or Allied soldiers to be written ob the inside on the lighter colored leather. Sometimes the GIs wrote their service number, either with their name or just the numbers. Names are usually too common to trace, whereas US service numbers could be. The worst method of IDs are those carved into the outside of the leather by the GI.