Bruno.M1 et al,
I have a hypothesis but am waiting for Piaget to confirm certain things.
Although Piaget has been making movements for other brands since 1874, they only started using their name on the dial as a Piaget branded complete watch circa.1942.
At the start of Piaget branding, they had access to movements that they were OEM suppliers for other brands. In the early years, speciality shaped movements with other stamped names were found in Piaget-cased watches. Piaget used Peseux cal 320 movements in the 1940s before they launched their own ultra-thin movements that started them on the path to world records until today..9P, 12P, 430P, 600P, 830P, 1200P and their variants.
The key point is that even from 1940s, Piaget marked movements with English words like "17 Jewels" and the "Adjustment positions" and not in French like "17 rubis".
Piaget did not just buy base movements and slap them into their watches. Some adjustments and decoration were added. Even the near-ubiquitous ETA 900 got the Piaget treatment.
The ETA 900 was used by everybody and easily sourced. Here is Piaget's version used in 1950.
The real Piaget movement does NOT look like the version in your posting. Maybe it was a "customised" ETA 900?
Regards,
MTF