Windows 10 S was recently unveiled as a more restricted version of Windows 10 aimed at students and teachers as well as being a response to Google's popular Chromebook/Chrome OS combo. One of the key restrictions when using Windows 10 S is which applications you are allowed to install. They must be available on the Windows Store, and Windows Store policies mean no third-party browser can ever make the grade.
As ZDNet explains, popular browsers including Chrome, Firefox, Opera, and Safari will never be available to Windows 10 S users. This is due to Windows Store policy 10.2.1, which states, "Apps that browse the web must use the appropriate HTML and JavaScript engines provided by the Windows Platform."
https://www.pcmag.com/news/353582/non-microsoft-web-browsers-will-never-run-on-windows-10-s