Microsoft will include the Edge WebView2 runtime with Microsoft 365 apps for enterprise version 2101 or later. This doesn’t mean they install Edge; it’s simply a software component to make it possible for Outlook desktop to run features developed for OWA. You can block the deployment if you like, but there’s really no good reason to do so.
Among the announcements made by Apple at their annual developers conference is the welcome news that iOS14 will allow you to replace the default mail app and browser. This is great news for people who use Outlook for iOS. And you might even consider Edge as a browser.
Modern browsers make it easy to pin websites to the Windows desktop and taskbar. Using OWA in this manner is great when network connections aren’t too reliable, like the flaky connections you often have on airline Wi-Fi networks. Other Office 365 apps work fine too when pinned from the browser, like the Admin Center, Planner, To Do, and Stream.