Does anyone know if people in Europe who buy it on Steam will be able to play it on the 19th?
Steam is also region-locked; it won't activate.
Sometimes it is possible to get around these things if someone in the earlier release zone sends a present to a person in the later zone, but it varies. It is, or was, possible to unlock a game that is not sold in one region if it is sent by a person in another region, for example.
In this case it is only a few days at least.