This has been lacking for a very long time now, along with a few others like even opening the tab menu. The ability to customize shortcuts and possibility to sync them across devices. I believe it's part of the core user experience things that defines a product these days as people want to get things done and mouse/trackpad is a real drag
A shortcut to duplicate would be even more helpful now that we have tab groups, to have a new tab to the right of the current tab, also inside the group.