'Missions & Rewards' Added to Nintendo Switch Online - IGN
Nintendo has released a "Missions & Rewards" update for Switch Online that allows players to earn Platinum Points by playing games and more, similar to Xbox's Game Pass Quests system.
www.ign.com
You can access them via the Nintendo Online menu on your Switch.
Right now you can trade your Platinum coins for characters from Super Mario Odyssey and Animal Crossing, meaning you can use them to give yourself a new icon including in-game backgrounds and game-related borders.
Seems like the Animal Crossing characters will change monthly depending on whose birthday is in that month. Right now you can choose from 34 villagers, 5 backgrounds and 5 borders.
Here's a possibility as an example: