I have now completed my Spotify integration plugin, the documentation for which is at https://spotify.logspot.top.
The plugin pulls your recently listened songs into your log in response to the /spotify slash command.
This uses Spotify’s authentication process which means the site does not store your Spotify credentials.
This plugin has been submitted to the marketplace, but in the meantime I would welcome any testing or comments. The plugin can be downloaded from GitHub: https://github.com/hankhank10/i-listened-plugin/releases/download/v0.0.2/i-listened-plugin-v0.0.2.zip