Had a look on one of the large supply houses and they only have the blue "Isofrane" style 20mm strap listed as part number: 032CA4752057 but do not have any of the back variants.
I'd like to order one through my Omega certified watchmaker and would like to give him the correct part # so he doesn't have to waste time looking for it. Any help given would be appreciated, thanks.

 

Hey, I know it's a really long shot to think you're still looking for that, but I found the part number for the black strap in 20mm, and it is: OME-032CA4752001.
I was looking for it myself, and will go get one as soon as stores reopen here.