I'm happy to announce that my barebones ActivityPub server, implemented in Node.js/Express, is now open source! I intend for it to be a reference implementation for developers who are adding ActivityPub to their own services, but also it is an application server that you can build on if you want.
In other words, t's a few hundred lines of code that lets you create Mastodon-compatible accounts that can accept follow requests and post stuff to their followers.
The @shop_keeper bot is just about done. It will rotate vendors and stock every day at midnight. Each vendor has a different specialty and accepts a different currency. Unique items will be generated each day. Eventually I plan to have them buy back items too.