I have found a partial solution. In Settings > Polls there is an option to enable any account to access their own Crowdsignal account. If this setting is not ticked then any user logged in to the blog will be able to access the admin user’s Crowdsignal account via the API key:

Multiple Crowdsignal Accounts This setting will allow each blog user to import a Crowdsignal account.

Unticking this option enable any admin user to go to Feedback > Polls and grab the embed code/shortcode/link from the account. However, the “add poll” button in the post editor screen still only displays the dashboard in the pop up.