Only test w/ Kyria and handwire.

app/boards/shields/petejohanson_pro_micro_handwire/keymap/keymap.overlay

@@ -0,0 +1,41 @@
+#include <behaviors.dtsi>
+#include <dt-bindings/zmk/keys.h>
+
+/ {
+	chosen {
+		zmk,keymap = &keymap0;
+	};
+	keymap0: keymap {
+		compatible = "zmk,keymap";
+		label ="Default keymap";
+		layers = <&default &lower &raise>;
+	};
+
+	layers {
+		compatible = "zmk,layers";
+
+		default: layer_0 {
+			label = "DEFAULT";
+
+			bindings = <
+				&mo 1 &kp A
+				&mo 2 &kp C>;
+		};
+
+		lower: layer_1 {
+			label = "LOWER";
+
+			bindings = <
+				&trans &kp D
+				&trans &kp E>;
+		};
+
+		raise: layer_2 {
+			label = "RAISE";
+
+			bindings = <
+				&trans &kp I
+				&trans &kp H>;
+		};
+	};
+};