Nintendo is currently running a "limited time" promotion where you can earn 1,000 My Nintendo Gold Points when you purchase or renew a 12 month family membership for NSO or the Expansion Pack service.
This offer is currently open to residents located in North America and will be available until 11th August 2024. These Gold Points can be exchanged for games on the eShop and other Nintendo Switch content.
Switch Online gives you access to online play, classic games, save data cloud services, the smartphone app, and some special offers. The Expansion Pack service comes with added extras such as DLC and more retro services.