I, as well as may many of the NVIDIA GeForce NOW users, are waiting for Nvidia adding new games. Some of the preferred games were already available, like Mafia series, but were removed from GFN. Later on, while I was waiting for that game to be available again I attempted…
According to https://en-americas-support.nintendo.com/app/answers/detail/a_id/55888/~/intellectual-property-%26-piracy-faq#s1q4 any games copying are illegal.
But I agree that it can be legal in your country or state: https://www.copyright.gov/title17/92chap1.html