A leaked Store entry of the first Microsoft Edge extension revealed interesting information about upcoming extensions support of Windows 10's default browser.
The store entry of the extension Page Analyzer is hidden from the Store application on Windows 10, the Microsoft Store website, and search engines currently which means that it cannot be opened unless you have the direct link.
The site that leaked the news,
Windows Blog Italia, did not reveal the link unfortunately which means that we have to rely on the information they provide instead.