Sites like Redbubble and Society6 are good to use if you want to offer products you can't easily/cheaply produce yourself, like blankets, phone cases, canvas art, etc.
But if you want to do simple things like small prints, charms, and stickers, you will see a higher profit margin if you find a manufacturer to make them for you and you price it yourself and handle shipping.
Zap Creatives (based in the UK) can do all sorts of stickers (including sheets!), charms, wooden and acrylic pins, and little standees!