If you find a used Baofeng at a hamfest swap meet, it is easy to check whether or not it is compliant.
Tune to any of the FRS or GMRS frequencies (see linked chart
Set it to the lowest legal power (see linked chart
Click the PTT (Press To Talk) button.
If you see that you can transmit, it is jailbroken.
If you cannot transmit, it is FCC compliant).
If it is an online sale, you don't have the test option. You'd have to trust the seller.