Some of the Sketch view tools, like Show/Hide Constraints, Slice Graphics, and Relax Mode, have an can be assigned keyboard shortcuts.
Show/Hide All Degrees of Freedom does not appear in the Tools->Customize list, so I can't assign it a keyboard shortcut. It also doesn't appear in the listing for Marking Menu customization.
(Also... Customize's Keyboard tab really needs a search box; Marking Menu tab has one, use that same thing in the Keyboard tab.)