Neutral Islands -
Shell Island
Helped Sailor Fist trainer, who is a criminal
Ravenna Tiberia, although I don’t remember if they have any shop npcs.
They’re poor so lore wise they might not have any, but if they do it’d be low level services, so a shipwright would just have a sailboat.
Regardless, they seem pretty desperate so if they can make even a little money then they’re probably glad to work with anyone willing to pay.
That should be all right now, no reason to make any other places neutral. Whitesummit is north (and is to the east) enough, and these two cover west and south. Shell island at the bare minimum should be a neutral island though.
A search bar and favoriting would make the inventory easier to navigate. Maybe custom filters you can add to weapons/armor to allow for faster switching between them.