We cannot turn back time and actually developing better legislation could address a lot of concerns. For example how do people legally de-transition? Currently there is no mechanism to allow Keira Bell (and others) to legally de-transition.
Legally distinguish between “full transition” and “gender fluid”. For example, Eddie Izzard uses “boy mode” and “girl mode” but as far as I’m aware has not legally transitioned. A lot of people may fit in this category and the law needs to set out how they should be treated e.g. can a person be misgendered if they swap genders depending on the day of the week.
Legal protection of children who suffer body/gender dysphoria from having medical treatment that cannot be fully reversed e.g. puberty blockers, surgery etc. (as determined by independent rigorous scientific studies).
Legally reinforcing and expanding existing sex based provisions such as sports, schools, prisons etc.
Legal definitions e.g. sex = male or female, gender = ?, woman = adult human female, transphobia etc. so everyone has the same understanding. Changing existing legislation to be clear if it relates to biological sex or gender e.g. gender pay gap becomes sex pay gap.
Legal right not to be outed (no pronouns,) .
Legally requiring public bodies (may be wider) to record biological sex, GRC sex and gender and being clear which is being used when publishing statistical analysis etc. This is important to ensure preventative healthcare is inclusive I.e. trans men are invited for regular smears etc. and other service provisions are accurately planned and targeted.
Including Maya’s ruling so biological sex is a defined belief and therefore a protected characteristic.
Etc………