Ask HN: Need validation whether either of these ideas have potential?

I have two ideas which I am researching. Do either of these have potential? These ideas are inspired by comments on an older post:

https://news.ycombinator.com/item?id=28436395

1. An app/website where you post once a day only. You can see your friends' single posts for each day. Chronological feed.

OR

2. An app/website where only pictures of animals, sceneries, architecture etc. are allowed. It auto-rejects any photo with humans.

Maybe an extra idea for both ideas: You are only allowed to post photos directly from the camera. Edited photos or photos from your photo library not allowed.

For paying the bills - no ads. Instead, the app will auto-delete all posts after 24 hours. Paid users are allowed to choose how long posts are around (1 day, 1 week, 1 month, 1 year, or permanent). They can also pin some posts to the top of their profile.

Thoughts?