u/throw_away_stress

I am aware of the obvious answer of d2d but was wondering if there's others out there with platforms that are worth publishing on? I think I saw ream and Eden's books when searching but not any actual information on using them.

I just have the two questions:

1. What's some places to publish taboo and what are the limits for them? EDIT: Im looking for SITES THAT PAY LIKE D2D
2. What's the best way to research the niches? Anyone have tips to keep in mind? I looked at the faq but that's only for Amazon and is 7-8 years old.