For those seeking out a federated and open alternative to Tumblr, Wafrn is looking extremely promising. It can speak both ActivityPub and AT Protocol, offers a ton of interesting features and customization, and focuses on making an incredibly fun experience.
This is what the thread looks like on Wafrn’s side: https://app.wafrn.net/fediverse/post/39562254-048e-4224-8445-36bba052ea91