I was added to a page as an Advertiser, and when logging in to my account through Facebook I'm able to access all Insights data. However, when I log in to Facebook Insights through Supermetrics Google Sheets plugin, I do not see any of my Business Manager pages.
I can see pages that have granted me access in the old way (just adding my personal account).
Facebook Business Manager actually has it's own API api and it cannot be used through FB Ads or Insights API.
We choose the next data source connector in to development by voting results. You can participate in the voting at https://support.supermetrics.com/discussions/topics/19000015989
We keep adding new sources on a fast pace, and for example following us on twitter: @Supermetrics you'll get the info as soon as new sources have been added to Supermetrics.