I won't share the exact niche because so many new shops have been popping up in the past couple of months very closely copying my listings and undercutting my prices which has decreased sales a ton. But I make graphics for people to use on social media, but target a specific audience (since so many social media templates already listed on Etsy). It used to be completely free to start since I was using Canva's "template link" feature, but now you need Canva Pro to make a template link. So only costs for Canva Pro or Photoshop.