refactor(boards): Move Pillbug to ZMK variant by default

Make the standard Pillbug board ID be `pillbug/nrf52840/zmk` or
`pillbug//zmk` by shorthand.

app/boards/mechwild/pillbug/Kconfig.pillbug

@@ -3,6 +3,6 @@
 
 config BOARD_PILLBUG
     select SOC_NRF52840_QIAA
-    imply RETAINED_MEM
-    imply RETENTION
-    imply RETENTION_BOOT_MODE
+    imply RETAINED_MEM if BOARD_PILLBUG_NRF52840_ZMK
+    imply RETENTION if BOARD_PILLBUG_NRF52840_ZMK
+    imply RETENTION_BOOT_MODE if BOARD_PILLBUG_NRF52840_ZMK

app/boards/mechwild/pillbug/board.yml

@@ -1,5 +1,5 @@
 board:
   name: pillbug
-  vendor: mechwild
-  socs:
-    - name: nrf52840
+  variants:
+    - name: zmk
+      qualifier: nrf52840

app/boards/mechwild/pillbug/pillbug.zmk.yml

@@ -1,5 +1,5 @@
 file_format: "1"
-id: pillbug
+id: pillbug//zmk
 name: PillBug
 type: board
 arch: arm

app/boards/mechwild/pillbug/pillbug_nrf52840_zmk.dts

@@ -0,0 +1,32 @@
+/*
+ * Copyright (c) 2026 The ZMK Contributors
+ *
+ * SPDX-License-Identifier: MIT
+ */
+
+/dts-v1/;
+
+#include <../boards/mechwild/pillbug/pillbug.dts>
+#include <common/nordic/nrf52840_uf2_boot_mode.dtsi>
+
+
+/ {
+    chosen {
+        zmk,battery = &vbatt;
+    };
+
+
+    // Node name must match original "EXT_POWER" label to preserve user settings.
+    EXT_POWER {
+        compatible = "zmk,ext-power-generic";
+        control-gpios = <&gpio1 7 GPIO_ACTIVE_LOW>;
+        init-delay-ms = <50>;
+    };
+
+    vbatt: vbatt {
+        compatible = "zmk,battery-voltage-divider";
+        io-channels = <&adc 2>;
+        output-ohms = <2000000>;
+        full-ohms = <(2000000 + 820000)>;
+    };
+};

app/module/boards/mechwild/pillbug/Kconfig.pillbug

@@ -0,0 +1,8 @@
+# Copyright (c) 2026 The ZMK Contributors
+# SPDX-License-Identifier: Apache-2.0
+
+config BOARD_PILLBUG
+    select SOC_NRF52840_QIAA
+    imply RETAINED_MEM
+    imply RETENTION
+    imply RETENTION_BOOT_MODE

app/module/boards/mechwild/pillbug/board.cmake

@@ -0,0 +1,7 @@
+# SPDX-License-Identifier: MIT
+
+set(OPENOCD_NRF5_SUBFAMILY nrf52)
+board_runner_args(nrfjprog "--nrf-family=NRF52" "--softreset")
+include(${ZEPHYR_BASE}/boards/common/uf2.board.cmake)
+include(${ZEPHYR_BASE}/boards/common/nrfjprog.board.cmake)
+include(${ZEPHYR_BASE}/boards/common/openocd-nrf5.board.cmake)

app/module/boards/mechwild/pillbug/board.yml

@@ -0,0 +1,5 @@
+board:
+  name: pillbug
+  vendor: mechwild
+  socs:
+    - name: nrf52840

app/module/boards/mechwild/pillbug/pillbug-pinctrl.dtsi

@@ -0,0 +1,56 @@
+/*
+ * Copyright (c) 2026 The ZMK Contributors
+ * SPDX-License-Identifier: MIT
+ */
+
+&pinctrl {
+    uart0_default: uart0_default {
+        group1 {
+            psels = <NRF_PSEL(UART_RX, 0, 8)>;
+            bias-pull-up;
+        };
+        group2 {
+            psels = <NRF_PSEL(UART_TX, 0, 6)>;
+        };
+    };
+
+    uart0_sleep: uart0_sleep {
+        group1 {
+            psels = <NRF_PSEL(UART_RX, 0, 8)>,
+                <NRF_PSEL(UART_TX, 0, 6)>;
+            low-power-enable;
+        };
+    };
+
+    i2c0_default: i2c0_default {
+        group1 {
+            psels = <NRF_PSEL(TWIM_SDA, 0, 15)>,
+                <NRF_PSEL(TWIM_SCL, 0, 13)>;
+        };
+    };
+
+    i2c0_sleep: i2c0_sleep {
+        group1 {
+            psels = <NRF_PSEL(TWIM_SDA, 0, 15)>,
+                <NRF_PSEL(TWIM_SCL, 0, 13)>;
+            low-power-enable;
+        };
+    };
+
+    spi1_default: spi1_default {
+        group1 {
+            psels = <NRF_PSEL(SPIM_SCK, 0, 40)>,
+                <NRF_PSEL(SPIM_MOSI, 0, 11)>,
+                <NRF_PSEL(SPIM_MISO, 1, 26)>;
+        };
+    };
+
+    spi1_sleep: spi1_sleep {
+        group1 {
+            psels = <NRF_PSEL(SPIM_SCK, 0, 40)>,
+                <NRF_PSEL(SPIM_MOSI, 0, 11)>,
+                <NRF_PSEL(SPIM_MISO, 1, 26)>;
+            low-power-enable;
+        };
+    };
+};

app/module/boards/mechwild/pillbug/pillbug.dts

@@ -7,7 +7,6 @@
 /dts-v1/;
 
 #include <nordic/nrf52840_qiaa.dtsi>
-#include <common/nordic/nrf52840_uf2_boot_mode.dtsi>
 
 #include "pillbug-pinctrl.dtsi"
 #include "blackpill_pins.dtsi"
@@ -20,7 +19,6 @@
         zephyr,code-partition = &code_partition;
         zephyr,sram = &sram0;
         zephyr,flash = &flash0;
-        zmk,battery = &vbatt;
     };
 
     leds {
@@ -29,20 +27,6 @@
             gpios = <&gpio0 20 GPIO_ACTIVE_LOW>;
         };
     };
-
-    // Node name must match original "EXT_POWER" label to preserve user settings.
-    EXT_POWER {
-        compatible = "zmk,ext-power-generic";
-        control-gpios = <&gpio1 7 GPIO_ACTIVE_LOW>;
-        init-delay-ms = <50>;
-    };
-
-    vbatt: vbatt {
-        compatible = "zmk,battery-voltage-divider";
-        io-channels = <&adc 2>;
-        output-ohms = <2000000>;
-        full-ohms = <(2000000 + 820000)>;
-    };
 };
 
 &adc {
@@ -88,7 +72,6 @@ zephyr_udc0: &usbd {
     status = "okay";
 };
 
-
 &flash0 {
     /*
      * For more information, see:

app/module/boards/mechwild/pillbug/pillbug_defconfig

@@ -0,0 +1,14 @@
+# Copyright (c) 2026 The ZMK Contributors
+# SPDX-License-Identifier: MIT
+
+# Enable MPU
+CONFIG_ARM_MPU=y
+
+# Use pinctrl
+CONFIG_PINCTRL=y
+
+# enable GPIO
+CONFIG_GPIO=y
+
+CONFIG_USE_DT_CODE_PARTITION=y
+CONFIG_BUILD_OUTPUT_UF2=y