In Osu! you can only turn off the overlay using Shift+Tab. But in other games (mainly FPS) you can toggle elements of the HUD. Instead of having to disable the entire overlay, we could create a section in settings called HUD. From there, you could have tick boxes (that are all enabled by default, obv) to disable elements such as HP, Accuracy (%), Pie-chart, Hit accuracy, Mods (if applicable), Combo, Leaderboards, etc. In addition, the key overlay option and the hit accuracy section could be moved into that area for ease-of-access.
Edits: Grammar etc
Edits: Grammar etc