All three of Google's document editing tools have just received an update to add a nice feature for physical keyboard users: navigation controls. The latest Google Docs, Sheets, and Slides have the same changelog highlighting this option:
* Support for keyboard navigation of on-screen controls
* Bug fixes and performance improvements
I don't have a physical keyboard right now to test this, but you should technically be able to move through on-screen menus and controls with your keyboard and without having to touch the screen. If you want to try it out for yourself, the latest version of each app is already live on the Play Store but you can also grab the files directly from APK Mirror: Docs, Sheets, Slides.