Most professional sports in the United States don't have any policies against women being in the sport. NBA, Football, Baseball, Hockey, etc.

None of them exclude women from playing in the professional leagues. Baseball did briefly in the middle of the 1900s, but that policy was reversed

It's just that, for these sports, the best women in the game have not yet been better than the worst men in the game. A woman and a man of equal height and weight are still not generally physically equal. Muscle composition and growth, bone structure, etc. mean that on average, women are less strong and less explosive than men, and most popular sports emphasize those attributes.

WNBA teams would often scrimmage against male pick-up basketball players for practice, and they would also often lose. These were just random guys in the area, many of whom didn't even play often.

The US Women's National Team played against FC Dallas's under-15 boys squad and lost 5-2. That USWNT went on to win the Olympics and the women's World Cup. The Australian women's team lost to U15 boys 3-0 and again to another U15 boys team 7-0; Arsenal's woman's team lost 5-0 to a U15 boys club; the professional squad Athletic Feminino in Spain lost to a U16 boys squad 6-0; and there are many, many more examples.

There is some research on evolutionary theory specifically about the vast differences in upper-body strength: "But even with roughly uniform levels of fitness, the males' average power during a punching motion was 162% greater than females', with the least-powerful man still stronger than the most powerful woman. Such a distinction between genders, Carrier says, develops with time and with purpose."

There are very few sports where this would be feasible, and most if not all those sports are not well-watched and make very little money: shooting, archery, ultra-marathons come first to mind.