As mentioned 9 months ago, the new French smart gas meter is called Gazpar and has a socket. So far I couldn't find any info about it but slowly, details are starting to emerge:

In this thread (in French), there is a link to a adaptation cable reference EER31130 sold by Schneider Electric for their own product but it looks like it could by used for any solution.

It also gives an indication of the type of socket (made by JAE but unfortunately I can't find the exact reference).

Schneider Electric's "pulse emitter" has the following characteristics which give other info about what the Gazpar might be (open collector (most likely) or reed switch):

• Compatibility with meters with pulse output of types: Open collector (electronic) / dry contact (mechanical contact), REED switch (magnetic) with the following characteristics:
• Voltage on the contact: 2.7 V (delivered by the Pulse Emitter)
• Closed contact impedance: <1 kΩ
• Open contact impedance: > 1 MΩ
• Pulse duration: > 66ms
• Delay between pulses: > 33ms

A suivre...