Using unauthorized NSP files can result in a permanent console ban from all online services. This means you would lose the ability to play any games online or access the eShop entirely.
Downloading copyrighted games from third-party sites is considered copyright infringement. Nintendo explicitly states that the only authorized ways to download games are through the official Nintendo eShop .
To enjoy the full experience, including its popular online multiplayer mayhem, you should acquire the game through official channels: Gang Beasts for Nintendo Switch - Nintendo Official Site