Starting 18 September 2021, the Redmond-based software giant will start pushing Chromebook users to its web apps, according to a statement it gave to About Chromebooks. The news blog also reported that only certain Office web apps, like Outlook, have an offline mode, and opening existing documents using Microsoft’s progressive web apps for Chrome OS while offline doesn't work. So, it sounds like this transition could be messy and not as fully featured.
It's worth noting that, as recently as July 2021, Microsoft's support documents recommended Chromebook owners install the Android versions of Office, Outlook, OneNote, and OneDrive to their laptops. Those support documents now state that those native Android apps are unsupported for Chrome OS users.
Microsoft doesn't explain why it is making this change, but it's a little ironic given Windows 11 now supports running Android apps. Honestly, it's probably just Redmond's way of competing with Google and Chrome OS yet again. Pocket-lint contacted Microsoft for a comment and will share more when we learn it.
Besides the offline editing issue, the web version of Office includes all the features you'd normally use, from word processing to checking email. To use the web apps, Chromebook users will either need to sign in with their personal Microsoft Account or an account associated with a Microsoft 365/Office 365 subscription