@Myles Gallagher It is possible but it is not pretty :)
You can create a page and embed the File Viewer web part on it.
Then edit the properties for the web part and choose "Range". Then You will be able to select a specific Sheet.
Save the Page and copy the url to it.

Open Your Team again and add a tab (of the type "Website" or "SharePoint). Paste the Url (or select the Page) and name the tab.
The result will look like this. Viewable but You will not be able to directly open it in Excel.

As i said, it is not pretty but it works if the purpose is just to display the data.
Hope that was a good enough answer.
Best of luck!
Regards, Magnus