Alt+V is is the visibility toggle shortcut in the assembly file, and also works when editing parts in the assembly context. HOWEVER, as soon as you open the part, Alt+V doesn't work and you have to left-click, select the part, right-click for the context menu, select to toggle visibility off; or find the part in the browser, right-click and toggle off part visibility.
It can be a jarring UX when switching between the Assembly to part files because you expect the same functionality but it doesn't work in the part context.
The key doesn't have any other binding in the part file so there is no reason it shouldn't work and allow you to toggle the visibility of parts, solid bodies, surface bodies, planes, sketches, axis', work points and more. Left-click to select the target object, then Alt+V to toggle visibility should be the functionality across all environments.
Please standardise this across the product.
