WIFI or Ethernet connections do not make a difference. WIFI is not as resilient to Ethernet. Ethernet is a more secure connection more stable connection and a faster connection by far then WIFI will ever be capable of.
Anytime you connect to the WWW/INTERNET (Wild Wide WEB) you should use encryption. HTTPS on websites is a start, VPN is another layer of protection from MITM Or Man in the Middle attacks. Not ALL VPNS are built the same and all do not offer encryption or strong encryption. So you need to beware when looking at these.
You should ALWAYS start security from the point of the device IE. your laptop, through a switch, into the router, and across the modem, into the vast WWW until it gets to an endpoint.
NOW NordVPN is what we call an ENDPOINT connection so your browsing ends up in say Ireland when you are really are in America. But then the site you are trying to connect with is in say Russia, so your VPN is not doing you much good on that last hop between Ireland and Russia.
Point to Point VPNS are not practical so you will have a hole between the ENDPOINT and the target site.
But VPN over an Ethernet connection is smart.
Now a true VPN will exterminate ANY connections to home devices until you shut down that VPN. Your network printer at home should stop working until you drop the VPN connection or you change settings to allow connections on that IP and subnet range.