I believe that’s the OME-98000024 strap that can be ordered through an OB. For custom you could enquire Jean Rousseau if they can make a similar one for you. Also keep in mind you will need to get an 18mm deployant to go with it.
I don't think they'll do curved. It's been a while but I'm positive I asked. https://www.swisswatchspares.com/pr...-20mm-98000024-black-leather-deployment-strap
take a look at https://www.combat-straps.com/ he made the Grey Alcantara for my A11 50SS and I'm now waiting for an alligator for my Carrera. lots of possibilities with ends, stitching, material, lining and deployants.