Starting in September, Microsoft will no longer support its native Android Office apps on Chromebooks. Instead, Microsoft will be advising those users to use its web-based Office.com and Outlook.com apps starting September 18.
Microsoft will continue to offer native Office apps for other Android platforms beyond this date. This is just a Chrome OS limitation being imposed by Microsoft, as noted by Kevin Tofel on the AboutChromebooks.com site on August 25. Chromebook users will either need to sign in with their personal Microsoft Account (MSA) or an account associated with a Microsoft 365/Office 365 subscription to use the web-based apps.
Tofel noted that as reported by Windows United, some Chromebook users had heard about Microsoft's plan to move them to the Web versions of its apps dating back to June this year.
Around August 13, Microsoft updated its Support page on "How to install and run Microsoft Office on a Chromebook" to reflect the coming change. That page now says, "The Android versions of Office, Outlook, OneNote and OneDrive are not currently supported on a Chromebook." The newly updated page advises Chromebook users to go to office.com to access Word, Excel, PowerPoint, OneNote and OneDrive. (Thanks to @teroalhonen for the pointer on the support page change.)
Before last week, this same Support page advised Chromebook users to install the native Android versions of the Office apps from the Google Play Store.
Microsoft's only public "explanation for this change is the web versions of the apps "provide(s) the most optimized experience for Chrome OS/Chromebook customers." I myself wonder whether this is simply yet another "Chrome compete" attempt by Microsoft.
Update (August 26): Here's an odd addition to this story. A Google spokesperson proactively reached out with this (surprising) statement:
"We're pleased to see Microsoft offer Chrome OS users a more optimized experience and embrace the open web. People love Chrome OS because it provides a speedy, secure, and simple computing experience and helps them stay connected while they work, study and stay entertained."
I subsequently asked whether Google officials were happy that Chromebook users running Office would no longer be able to work offline once Microsoft makes this change. No word back.