Adding Custom App to Zendesk Sell Contacts List Menu for End Users

We’re currently developing a custom Zendesk app and aim to make it accessible for end users directly from the Contacts list under the Apps menu. We’ve noticed that the Mailchimp for Sell app is available in this menu, and we’d like to achieve the same positioning for our private app. However, we're unsure how to configure it to appear in the Apps menu.

Has anyone successfully added a private app to this section? Any guidance on how to set this up would be greatly appreciated.