The earliest 38hs had a pinned magazine release.
I agree it is a last model 'cigarette gun' made for the elements of the American Third Army that occupied both the Walther plant in Zella-Melis and the Sauer plant in Suhl, about three miles apart from one another.
The American Army subsequently pulled back to the West in accordance with Allied powers agreements, i.e. we backed up so the Russian army could control what was to become the DDR.
Of course, the Walther and Sauer clan packed up in a hurry and came along with us. Their workers, not so lucky.
Most of the guns were assembled from parts in the plant with no thought to matching up slides and frames in exchange for cigarettes and rations.
The majority of the frames were already numbered, some in sequence and a separate run of frames were made starting at serial 1. But un-numbered frames are not unheard of.
Yours appears to be one that fits neither standard occupation category, as it appears to have been built with a nice looking mix of finished and in the white parts. Lack of rust on it is a definite bonus.
I've never read of a conclusive reason for the TG notches that are only found on these mid 1945 guns.
Value is definitely over a standard Army proofed or police gun, not to mention a commercial.
Auction might be the only way to know for sure, but I believe it would fetch 750 or more easily.
Sauers like yours don't show up for sale that often and yours is in definite collector grade.
Keep it oiled and get another instead if you want a shooter.
My 02, JT