So what would it take to pass a law to make abortion legal in all 50 states? Regardless or Mancin and Sinema, there are a few Republican senators, such as Murkowski, who are opposed to this decision.
A constitutional amendment. Any law straight up says "States can't pass laws that ban or restrict abortion" would be challenged and struck down by the court. Not even just by this court, but really any. The federal government is good at spending and taxes but actually restricting what states can or can't do isn't how the US government was structured. Stuff like "the drinking age must be 21" is a good example of how complicated stuff is to actually get passed in a way that withstands scrutiny.