Yea, I really miss Outposts having their own unique stock of items by region. People complained a bunch about it back when it was a thing, but I always felt it was short sighted. It would certainly make the Shop menus less cumbersome now that we have an additional 3 or so years worth of cosmetics that have been added to the stocks over time (with no doubt more to come over the next 6 or so years of the games intended lifecycle). Now they are all just a massive mess of stuff. I would really love to see this be reimplemented in the game.
I still stand by that I would love to see Taverns have different house brews of Grog that cost coin but convey a limited effect of some kind (meaning that when you drink it a timer starts counting down immediately so that the effect it gives wears off - nothing too extensive, at most like 5 minutes). You could still get free refills on your basic Grog there as well, this would just be an added option that costs some coin since it would provide some limited benefit. Each Tavern could have a unique Brew that they serve (some dialogue even supports the idea that this is a thing). Your Ship would always contain the generic Grog as well so if you want to grab one of these buffs you have to swing by an Outpost and hit the Tavern.
Just for a little more Shopping experience, I'd like to see the Resources spread out a bit across the Outpost or some new options added to the various spots. Honestly, the Shipwright could sell a basic Rowboat for some coin (the one that just has a Lantern on the front) - much like Supplies this would give a choice to pay some coin for access to some basic stuff at the start of a session, or you can invest some exploration to go find one of the upgraded options out in the world. I'd also be very open to the Gold Hoarders selling a single Collectors Chest for some coin, in much the same way we can get a Storage Crate from the Merchants (to sort of indicate that they double dip on Chests we cash in by taking the Gold - giving us our cut - and then selling the Chests right back to us to try and get back more of that cut like the greedy folks they are). That would give you a little more reason, if you were inclined to do it, to run around and do some shopping before you start your session (or even part way through your session).
This would really give some more purpose to the Outposts, in particular at the start of a session, but also reason to potentially drop by in the midst of a session. You'd have unique stocks at Vendors, a series of supplies for your Adventures, and access to some temporary Effects that would be minor but might make something you plan to do slightly easier. I'm sure not everyone would agree with all of that, but it is the approach I would consider personally.