The four-letter route
Trace ONYX from 1 at row 3, column 6; 2 at row 3, column 7; 3 at row 4, column 7; 4 at row 5, column 7. The cells read O → N → Y → X, so all four positions match the supplied spelling in order.
Take one step right and then two steps down. This path spans three rows and two columns, making one turn across two straight segments. Three of its cells visit an edge. Marking the route assigns the first four of the board’s 43 open cells and leaves 39 cells for the other five answers.