Oof. Fucking FIDE. Trans women should be able to compete in the women’s sections.
About the gender gap - the gender gap in performance is a statistical relic of the participation gap. Control for participation and the performance gap vanishes.
Women’s sections exist to help promote participation and competition in that cohort. Its the same reason junior sections for kids exist, senior sections for older adults exist, and ratings limited sections like U1200 and U1500 exist.
Unlike other sports, a trans person would have no physiological advantage or disadvantage competing across gendered sections.