What's a good marketplace niche?

Hello indie hackers! Sorry for the very generic question 😅

I have an existing Marketplace Mobile App complete with an Admin Portal, and a website store. Right now I'm targeting the Food niche, but there are already a lot of competitors in this space.

That's why I'm thinking of a new niche to target. There are a lot of options (medicine/groceries/sportswear/baby clothes) but I'm wondering if maybe there are underrated marketplace niches that has not yet been addressed yet.

What's a marketplace niche that hasn't been addressed yet? 😄