The latest Microsoft Edge Canary 76.0.160.0 update has enabled dark mode support on Windows 10 and brought fully functioning Spell Checker to new Edge browser.
The Microsoft Edge Chromium browser doesn’t support dark mode by default on Windows 10, you need to visit edge://flags page, and then you’ve to enable “Microsoft Edge theme” flag and restart the browser.

READ: How to Enable Dark mode in Microsoft Chromium Edge on Windows 10
Doing this no longer required in case of latest Edge Canary version 76, the following OS theme flag has been enabled by default and the new Edge now synchronizes with Windows 10 dark mode. For it to work, ensure you’re using the latest Edge Canary.
Click on Start > Settings
Personalization > Colors and change app mode to “dark” to see Edge going dark instantly

Spell Checker is now available in Canary and enabled by default in Languages Settings.

Other changes:
Like in Chrome 76, Flash Player is blocked by default in Edge Content Settings and you’ll receive Flash player will no longer be supported after December 2020 notification on every startup if you change Flash content setting to “Ask First”.
READ: Chrome 76 in Canary disables Flash by default and showing Flash Player depreciation Warning
PWAs can now be installed from the address bar with a single click: When you visit PWA site in Edge browser, a visual indicator will appear and allows you to install PWA on your computer. We’ve reported about this before and we can confirm Chrome 76 is getting this feature. Till now the PWA install option is hidden in the menu, now it appears for PWA sites in the address bar.
READ: Chrome 75: Install Progressive Web Apps (PWAs) from Omnibox
What’s your take on these improvements?