the states rights movement.

The pro-slavery movement?

I might be confused about what you’re saying.

In general, at the state level, you cannot prevent someone from going to another state even if you suspect they’re going to do something there that’s illegal in your state. Once you cross state lines, you’re subject to the laws of the state you’ve entered, and to federal law. Interstate crimes, like trafficking, fall under federal law, and that’s when the FBI gets involved. In addition, the drinking age policy was enforced, not by state law and not even by federal criminal law, but by the federal government passing a policy that restricts highway funding. Oklahoma could not criminalize traveling to Louisiana to drink “under age,” the feds had to get Louisiana to change their state law.

Texas can’t arrest you for flying to California to legally smoke weed. They can’t arrest you for going to Las Vegas to gamble. What they’re trying to do is make traveling while pregnant a trafficking type of crime such that existing the state while pregnant is a suspicious act.

The current SCOTUS has made some ridiculous rulings, so I wouldn’t want to gamble on this, but I honestly don’t think that it’s going to be more than political virtue signaling on an obviously unconstitutional law until the republicans take power at the federal level and pass a national anti-abortion law that permits federal agents to arrest patients and physicians in New York and California as well as having the sheriff do it in texas.

Which is interesting given that the federal government also says that they claim extraterritorial jurisdiction on citizens abroad, so even if you do something in another country that's legal, but illegal in the US, they could still prosecute you for it.

I think it's also legal for Texas to make a law that'd allow them to arrest someone for travelling to Colorado with the intent to smoke weed

No, it's not. The "commerce clause" in the Constitution gives Congress the power to regulate interstate commerce, not the states. States are separate legally. They can't decide what other states do in their own territory, and they can't pass laws restricting people traveling for that commerce.

If something is legal in one state and illegal in another, simply passing through a state to get to another literally can't be restricted. This is the literal definition of the commerce clause, especially because healthcare in the US is a for-profit enterprise.

In fact, the healthcare facility could sue Texas in civil court for causing them damages by reducing their customers. It's a direct harm to their business.

It’s legal for a Texas resident to smoke weed in Colorado.

This is what they asked (although not very clearly) and the answer as you said is yes.

I think it’s also legal for Texas to make a law that’d allow them to arrest someone for travelling to Colorado with the intent to smoke weed

It's not. It's literally unconstitutional. Even Kavanaugh got that part right.

In his concurring opinion in last year’s ruling overturning Roe, Supreme Court Justice Brett Kavanaugh contemplated whether states could restrict their residents from getting abortions in other states: “In my view, the answer is no based on the constitutional right to interstate travel,” he wrote.