I've created an activity module to enable participants in Moodle courses to collaboratively edit office documents (text, spreadsheet, presentation) inside the course and save the documents back to Moodle.
The editing is done using the ONLYOFFICE Document Server online editor. It works similar to Google Docs, but with the difference that the documents stay within Moodle.
The plugin can be downloaded from https://github.com/logicexpertise/moodle-mod_onlyoffice
While the plugin is functional, it is still missing a number of key features, particularly ability to be backed up and support for the new privacy API. I also plan to add for grading at some point, and improve the UI/display on the course page.
In the meantime, feel free to take it for a spin, and provide feedback via replies to this post or on the plugin's Github page.