Running narrow.narrow-file shows a QuickPick listing of all lines in your current file. Type to narrow down to matching lines. Hit enter to move your cursor to the selected line.
Running narrow.narrow-git shows a QuickPick listing of all lines which were added since your last commit to quickly jump to your most recent work in a file.
Keyboard Shortcuts
Narrow does not assign keyboard shortcuts by default.
Open your keyboard shortcuts json (Preferences: Open Keyboard Shortcuts (JSON)) and paste this snippet to get started: