Literally the only reason we have a separate category of women's sports is because, on average, women are physically weaker than men. If both sexes could compete against each other, women would barely exist in elite sports. If that wasn't the case, there'd be no justification for excluding cis men from women's sports. After all, being male is "just another advantage" like being tall, right?
On average, cis women are physically weaker than trans women also, and so the same logic applies.
The only equitable solution I can see is a third category of trans sports, where trans people compete against each other
No, not any woman stronger than the average for women, because by definition the leading woman will always be stronger than other women.
At the same time, plenty of cis men are weaker than the average female athlete, but we don't let them compete.
We exclude all males as a category, including former males, because on average they have an unfair advantage. Attempting to make exceptions based on individual performance isn't feasible.
Effectively, women's sports are like amateur vs pro competition. You don't let an ex pro play in an amateur match, even if they're not as strong as they once were.