I was able to bring Substack notes to Mastodon toots using the “Copy code” in the “Embed” menu. It involves:

1. copying the embed code

2. generating an atom feed of the embed contents with Jekyll (collections)

3. building the website

4. a Py script that: parses the feed file, cleans the text for Mastodon, creates a queue, uses a scheduler, interfaces with the Mastodon Python API, keeps tracks of the notes already posted

Overall it’s a semi-automatic process that involves Python, Ruby, XML, HTML, JSON Lines, Systemd unit file, YAML.

This will save time via automatic re-posting.