Introducing #Hollo. Hollo is an #ActivityPub-enabled single-user microblogging software. Although it's for a single user, it also supports creating and running multiple accounts for different topics.
It's headless, meaning you can use existing #Mastodon client apps instead, with its Mastodon-compatible APIs. It has most feature parity with Mastodon. Two big differences with Mastodon is that you can use #Markdown in the content of your posts and you can quote another post.
Oh, and Hollo is built using #Bun and #Fedify.