In Excel 365 pressing ALT shows the shortcut key in the ribbon ( if enabled in options). The issue is that the ribbon looks now like google maps. In Edge pressing ALT sets the focus to the "...". What to do next is left as an exercise for the reader. In Teams, pressing ALT does nothing and the Help button has only "Themes", "News" and "Training" .
At least on macOS and Windows the shortcuts are shown in the (traditional) menu bar. With GNOME's use of hamburgers, it's anyone's guess. As someone who likes shortcuts, I found it very hard to figure out shortcuts in GNOME apps that have a lot of functionality hidden away. (Aside from keyboard shortcuts not being very consistent between apps on Linux.)