Hi, first of all, thanks for this great project!
I could not find a discussion dedicated to this exact idea/feature so I am starting one here.

Feature Description

It would be great if there was a way to add new modules/components to the sidebar using extensions. Currently, the main purpose of the sidebar is to expose additional context/view-specific metadata and tooling (e.g. revisions, comments, shares in the details view). Additionally, there is also a sticky section at the bottom (currently only contains the activity log) that shows the same elements regardless of the current context/view. I believe it would be great if an extension could add custom modules/components to both of these sections (1. contextual section, 2. sticky section).

For the contextual section, the extension would have to define a condition that determines if the sidebar component should be visible (e.g. only show the component for specific collections, layouts, etc.).

The custom components (both contextual and sticky) should also have access to the current context (e.g. which collection/item is currently displayed)

Example Use Cases

• Custom import/export/share functionality
  • Generate some custom shareable URLs
  • Send/Publish content to some third party tool/app
• Manage custom backend tasks (e.g. tasks triggered by a directus hook, like generating content thumbnails, etc.)
  • Show currently running tasks (sticky, or contextual for specific content)

Alternatives

It would be possible to create custom layouts or modules to implement some of the examples above. However, using the sidebar would be a more elegant approach in my opinion. Custom contextual components would also provide an easy way to extend the functionality of the existing layouts/views and extensions would not have to recreate existing functionality in custom layouts/modules (e.g. displaying a collection and allowing multi-selection to perform some batch operation).