The flip up lids are specialised for outdoor use. Is this what you want, or do you want a normal twin socket for indoor use? I don't think the French use switched sockets. Surface mount twin socket are available but won't take UK style 3-pin plugs. We have a couple of members who are well versed in the French regs that will post to clear things up.

French face plates, every producer has its own range, only for French back boxes. Sometimes you'll need the retrofit versions, with < griffes>. The flip up lids are useful also for use in a garage or in a industrial environment, where the belt and braces approach reminds us of Paris: the so called < pose façon métro >. Even more safety with the < prrincipe de la goutte d'eau >.

I think that I understand what you are trying to achieve, you want it to still look industrial after the conversion to habitation, chacun à son gout and it's you that have to live in it, my question is who is the target audience that you want to see the industrial look?

Brits would make the connection but you are in France and French industrial premises dont use metalclad sockets, metal backboxes and metal conduit, they use ones destined for zones humides and plastic conduit.

What you propose were you able to achieve it would look very odd and offputting to any French person and one must always think to when the house may be sold in the future and also you could well end up failing the diagnostique electrical for matériel non conformé.

You could attach a French faceplate to the steel backbox if you find one with the right hole centres, unlikely, you would have more chance getting one with griffes to hold in place (possibly with some packing screwed to the inside of the backbox) but they have not been sold for years and even when they are not bodged they will often fall out when a plug is removed.

I did use the griffes on a French IR controlled lightswitch (bedroom lights switched by the TV remote)in a standard UK galvanised flush pattress years back, ironically it was bought in the UK from CPC and I could not work out why the hole centres were incorrect and what the griffes were for, on moving to France it all fell into place.

I completely agree, I have bought and used all the above and also incorporate gaine ICTA for some transitions.

I can't sack all the electricians though!!!!

I'm glad someone answered the actual question you asked.  I would like to add one more thing.... WELCOME...