A Polaris solo that properly addresses her character history and gets enough promo for people to know it exists would sell a lot more.
She's never been given real use by Marvel, and her history is a mix of scenes that didn't consider her perspective enough, and huge gaps waiting for stories to fill them. People would want to read the hidden history she lights up along with all the undercurrent topics she offers (multiple forms of trauma, mental health, alternative and creative ways to use her power set, the importance of a mutant identity, development as an independent woman away from X-Men and Magneto and the like, etc).