can I I use one to receive internet from a router, and the second one to "send" internet to another device? (which is supposed to be a Samsung Dex station)?
Of course you can. If you want only point-to-point communications with this station, you can easily do so using static IP addresses. If you want the station to be able to use the NUC to access the Internet, however, you will need to support the NUC being a Router as well.
Hope this helps,