I don't think you have any other option than pre-owned and use a good authenticator
I first asked for and got authentication on here and subsequently paid with my own photographs
But no-one sensible would not share concerns about authenticity.
It has to be pre-owned HOWEVER there is a part of Hermes offering a special order service, I have seen it mentioned on here (I don't mean SO for Kelly or Birkin) and I did wonder if they would make make one, but I think the premium would be something like three times what the retail cost for a stock item might be.
I looked at VC there are two from the same seller!!!
I searched Hermes Briefcase, you have to try all the permutations of Hermes, Kelly, sac, Depeche, briefcase,
Good luck hunting