We had a long thread (not this one, which I just found, but this one) in which we thrashed out the legality of a state criminalizing people for going to another state to do something legal there. No consensus was reached, because there seems to be no precedent and the powers of a state government could not be agreed upon. Legislators in several states have introduced bills criminalizing this for the purposes of an abortion but none reached passage.
The argument for a federal law would differ. A federal law not only could but must apply to all states. Laws already exist that criminals cannot escape punishment for federal crimes by moving across state boundaries and courts have approved them.
But pregnancy is not a criminal act, as already noted, and any government that could criminalize it would exist only in an alternate reality, so anything there is possible.
Making abortion a federal crime, illegal everywhere, could provide justification for stopping someone, although the legal rationale would have to be criminal conspiracy if the women were apprehended before the abortion. Even in such a case, the charge would be a federal crime, tried in a federal court, and the state wouldn’t come into it.
There’s always a “but” in all legal matters. In the Slaughterhouse Cases of 1873, the Supreme Court ruled that the “distinction between citizenship of the United States and citizenship of a state is clearly recognized and established” thereby gutting the 14th Amendment. As far as I know, the statement has never been definitely overruled since although all courts have pretended that such an atrocity never existed. That implies that a state’s rights obsessed Court could reach back to it as precedent for a return policy.
I think we’re back into alternate reality, but IANAL.