The basis of this idea is largely rooted in pirates not having a post-creation path to nobility. Nobility isn't exceptionally common post-creation for a lot of characters of course but the difference is that even commoner characters can try and wheel and deal their way into a landed nobility appointment. Pirates however don't have something equivalent to try and vie for.
To this end I'd propose either some kind of noble equivalent path for pirates. Maybe concluding in identical benefits to being a noble, or maybe tailored with benefits similar to nobility but with twists to make them more thematic for piracy, I don't have an overly specific vision for how it'd look but I think it would be interesting.
Implementation could vary but if accepted my own suggestion would be to perhaps tie it to some kind of recurring fee or one massive lump sum meant to represent being such a lucrative pirate that you have attained some sort of 'notorious recognition' for your plundered riches that commands begrudging respect even amongst those who loath the noble pirate. I'm envisioning a required sum totaling at least a million gold but I would personally push for something like five million to emphasize the gratuitous wealth the relevant pirate has amassed.