For as customizable this game is with cosmetics I feel there all really similar and to get actually unique cosmetics you either have to pay double told in the black market (comparing price to the NPC shops at each outpost) or a few hundred doubloons on the black market (for a full set sometimes will be just short of 200 though) and you dont get doubloons very often and when you do it's like 5 doubloons unless you completed a commendation that's worth like 25 or 15 even. Yes I know reapers chests exist but no one goes for them unless provided for them like from a fort or something. So to kind of answer the title, for cosmetics you could glad more clothing options like those one eyed glasses things that the merchant alliance has or patched for your pirate to wear on there shirts or hats or even pants, lastly it would be cool to have just more styles from the usual NPC shops. And the second question more ideas to earn doubloons you could have voyages that earn you doubloons based on rep level (plus that would get people doing voyages more often) or just add a voyage to earn doubloons that cost in gold and can earn you 100 to 150 doubloons but you can only do these once a week so you dont just repeat the quest 10 times and you have 100 doubloons that would be dumb
Just thought I'd get that out there
Stay safe my fellow pirates and keep grinding
