New Microsoft Edge browser based on Chromium which is available for a manual download for Windows 10, Windows 7, Windows 8 and macOS supports installing extensions from Chrome Web Store, but not themes. After getting feedback from Edge insiders Microsoft has decided to allow themes installation from Chrome Web Store in its Edge browser, you can enable the support if you run New Edge Canary with a command-line switch.
If you now try to add a theme from Chrome Web Store to Edge, you’ll get an error saying that “Themes and apps are not supported in Microsoft Edge”. In the past, we’ve covered you can install a Chrome theme in Chromium Edge by downloading extension and dragging and dropping it to the edge://extensions page, this no longer needed, you now just need to append a command-line switch to Edge Canary Target path to achieve that.
Enable Chrome Web Store themes installation support in Microsoft Edge browser
1. Ensure you’re using the latest canary version 81.0.395.0 or higher, right-click on its desktop shortcut, select properties,
2. In the Target field, after msedge.exe” add the below switch
--enable-features=msAllowThemeInstallationFromChromeStore
5. Click ok and Apply
Installing themes from Chrome Web Store in Edge browser
1. Visit the Chrome Web Store and navigate to Themes section
2. Select one of the themes published by Chrome team or other
3. Click add to Chrome, the theme will be installed. You may need to reset the Edge browser or follow the procedure mentioned here to uninstall a theme. [Thanks to Leo].