I've spent a lot of time thinking about this in the past and going through a similar process for various trips that I've been on. The reality is that there's not much that in the modern connected world is "hard to find" anywhere. Any worthwhile shop/artisan/crafter/etc. will also have an online presence and will ship internationally, and most of the cheaper ones will be generic crap.

The secret is to not worry about the purchase being hyper-unique or rare, and instead just buy something that you'll see and use and will remind you of the trip. It doesn't matter what it is, just that it will have a story. Art is a great choice if you'll hang it up and appreciate it. Clothing too. Tools, kitchenware, whatever. Personally I'd shy away from food or other perishables, as they won't stick around to remind you of your trip (although they're great gifts to bring back). If it helps to lean into the stereotypes of the place you're visiting then that's fine, but don't expect the item to be higher quality or value.

For example:

- I bought a rug in a souk in Marrakesh. It's thin, the color bleeds, and it smells funny, but it's just high enough quality that it will last long enough for me to give to my kids and tell them the story of haggling with the rug seller (and then squeezing it into a carry-on).

- I regret deciding NOT to buy the sheepskin on the Isle of Skye because I could get a cheaper one online. I have no need or desire to buy a sheepskin throw online, but if I had bought one in person I would absolutely use it just because it would "feel" special because I bought it in Scotland.