Hello Loris,
I have Urban Platforms on a touring bike which I like a lot. The measurement that you seek is 33.3 mm. I like the large toe tab on these pedals for quick orientation from a stop to get a foot in place before the cars overrun me. According to the MKS website the Urbans are slightly wider and lighter than the GR-10's.
I have a large 48 EU shoe size and the Urbans feel good. I've fitted them with large plastic double strap clips (ala fixie) which are quite comfortable enough with soft shoes. But I have to be careful with toe overlap on the front fender (mud guard) and 27" wheels!
Hope this helps. Perhaps I will see you when I ride along the Canal du Midi (as soon as the virus subsides).
Tom