samples/drivers/uart/passthrough/boards/nucleo_l476rg.overlay

/ {
	chosen {
		uart,passthrough = &uart4;
	};
};

&uart4 {
	pinctrl-0 = <&uart4_tx_pa0 &uart4_rx_pa1>;
	pinctrl-names = "default";
	current-speed = <9600>;
	status = "okay";
};