I remember buying a new replacement thumb shifter that had the exact same replacement part number as the original one that broke. The original one had a black face and the replacement was sliver. LBS told me they stopped making the black one. Had the same thing happen recently on a lamp lense for an automobile.
Given the buyer is aware of different variations of this lever, I think seeing the actual item is a perfectly reasonable request. Of course, the seller is entitled to keep the box sealed.
I'm not on board with the advice to just buy it and return it if it's not right. It might not be the precise variation the buyer is looking for even though it is accurately listed. If everything in the listing is accurate, the seller does not have to accept this return (listing states no returns accepted). If the seller were to accept the return, the buyer would likely have to pay for the shipping.
As a buyer wondering if this is the exact item I'm looking for, I'd move on.