Without any fanfare, Microsoft finally made Word, Excel, Outlook, and PowerPoint available for (apparently) all Chromebooks via the Google Play store. Chrome Unboxed confirmed their availability on the Pixelbook, Samsung Chromebook Pro, two Chromebook 15 models, and the Acer C771.
https://www.notebookcheck.net/Microsoft-Office-finally-available-for-all-Chromebooks.266710.0.html