GPS coordinates for 1.5M addresses

Two things:

1. OSM does not contain all addresses in France today. According to the taginfo statistics tool for France, we have about 800.000 addresses (all being added manually, it is already a huge dataset). So, do not expect that OSM will provide you "1.5M addresses in France" today. All of them are imported manually into OSM by contributors either based on local survey or, most probably, from the French Cadastre. If you fill that some areas in France are lacking addresses, you can help by contributing and adding them yourself.
   
2. even if the database would contain all your required addresses, OSM is not providing "services" like the one you are asking. Either extract the data yourself : you can find database extracts per country by several providers and use an extraction tool like Osmosis or Osmium (see the list here). Or you can contact a company offering commercial services around OSM to do this for you (listed here).