Selenium 4.0.0 will have proper support for Microsoft Edge (Chromium based), including support for the IE mode.
Notable (non-breaking) Changes:
ExtendedEdgeOptions derives from EdgeOptions instead of ChromeOptions
EdgeBrowserFactory.CreateEdgeDriver returns an EdgeDriver instance, creating using the ExtendedEdgeOptions
EdgeBrowserFactory.CreateEdgeDriverService returns an EdgeDriverService instance
Other notable changes (from https://github.com/SeleniumHQ/selenium/blob/master/dotnet/CHANGELOG )
Drivers supporting Logs will be marked with the ISupportsLogs interface.
Updated to allow .NET to disable W3C mode for Chrome 75+. (Fixes )
Added ability to install/uninstall Firefox add-ons.
Added support for Chromium Edge.