It's very long so there's basically no chance of doing this all in one sitting but...whatever, let's see how far I can get this afternoon with 
TBH I may get stuck with basic setup, I've written a lot of javascript but I've largely avoided having to learn JS/TS package management. 😂 (Fun fact, I learned Vue over React or Angular etc because you can build absurdly complex apps while still just importing vue via script tag)
Creating your own federated microblog | Fedify
In this tutorial, we will build a small microblog that implements the ActivityPub protocol, similar to Mastodon or Misskey, using Fedify, an ActivityPub server framework.
unstable.fedify.dev
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