Aside from calling Yamato a Straw Hat Pirate within the current merchandise, isn't this the next best thing?
The thing is that merchandising isn't done by Oda. The companies buy the rights to do stuff and do stuff.
Also I don't know much about the merchandise, but when did the coins convey Jinbe as a Straw Hat Pirate? Was this after Luffy invited him in Fish-Man Island?
Nope, it was pre-timeskip, I believe in the post-war days.
The coins were a very special case because it wasn't just Jinbe + Straw Hats, but several other characters, and some characters got copper coins, some got silver coins, and only the crerw got gold coins. Jinbe was the only non-SH with a gold coin.
Now, to this day we don't know if the company had insider info (maybe Oda suggested giving Jinbe a gold coin) or just made an assumption and hit the jackpot, thought in this case I feel Oda or his team could have veto'ed the Jinbe coin if they wanted to avoid confusion/spoilers.
That IS quite something supporting Jinbe way back.
Yes, it was, in essence, a very special case.
If merch starts calling Yamato a Straw Hat in some non-subtle way like that, then the deal would be almost done. But just lumping them together is not enough.