My plan is to add Nostr support to our Peerhub software next. 
 
Right now, you can login to any Peerhub-powered site with a peertube, mastodon or other fediverse account and post pseudonomously with a throw-away account. It also enables donations through Likes and Tips so if the abused needs some monetary help, there's that. 
 
Once I can add Nostr too, then of course Zaps are possible too. 
 
Images, videos, mp3's can be added to their post, and the site admin or someone can approve the post before it is publicly accessible if desired. In addition, the user can even add a password so that the post can't even be viewed publicly unless the viewer enters the correct password. 
 
As for anon emails, that's kinda tough, but there are throw-away email providers out there, but imo it's better to just use an encrypted messaging system such as matrix, session, simplex, keybase or maybe even nostr (I've heard there is encryption coming for that as well). 
 
Depending on your budget for this project, I could even get you your own server for this so that all content being uploaded is owned and controlled by you, and even replicated to off-site servers for data redundancy and legal security/immutability through S3/minio/IPFS. 
 
My Peerhub server software is totally free btw, you just need to install it on a decent webhost. Ping me if you'd like some help with it or email: 
agorise@pm.me 
 
Best of luck with your project! <3 
  ken