I’ve written a fediverse server framework that implements ActivityPub in Deno. There are still many features to document and add, but the basic behavior such as creating and following actors and sending and receiving activities works well. It’s also been tested with Mastodon and Misskey.
There’s also a federated single-user blog in the repository as an example project. If you’re interested in building a fediverse server app, take a look at the project! Thanks!