That's why I mentioned measurements not vanity sizes. Give me waist, hip, and in-seam in centimeters or inches and let me filter by picking ranges. That's infinitely more useful than gendered S/M/L "sizes".
No it is not. You would end up getting styles aimed at the wrong gender..
Vanity sizing means the items is listed as a smaller size than it truly is, changing the units doesn't change anything. They can still say its 28" when its really 30".