Regarding Manurhin versus Walther PPs, there’s some interesting history there.
Germany was banned from small arms production for 10 years following WWII so Walther contracted iwoth Manurhin in the Alsace region of France (ceded to France after WWI, so “French” Germans).
Walther made the forgings for the slides and frames which were then shipped to Manurhin for machining. Manurhin also made the small parts, blued and finished everything, assembled 5em and proofed them.
Once Germany was allowed to produce small arms again they started “making” the PP and PPK in Germany again. However what this meant was that they continued to forge the slides and send them to Manurhin who again milled the frame and slide, made all the small parts, and then finished everything except the slide. They then shipped the parts to Walther where the slide was then induction hardened and blued, roll marked by Walther, assembled and then proofed in Germany. Under German law finishing, roll marking and proofing the slide was enough to count as manufactured in Germany.
One of the effects of the slide being blued in France by Manurhin and the slide being induction hardened and then blued by Walther is Germany is that the bluing on the frame and slide usually doesn’t match.
One look at yours told me it was made prior to 1986 when Walther discontinued its agreement with Manurhin and finally started making the complete pistol in Germany.
Walther pistols are of course more highly regarded and the pre war specimens are extremely well made. However the post war the Manurhin pistols have the advantage of matching bluing. Many PP fans also regard the post 1986 entirely Walther made pistols as objectively being lower quality than the Manurhin made pistols. By that time they had 30 years of experience making them while Walther was just starting over with them again.