I have been suggested by someone with YAML knowledge to use anchors, but I don't know if these are supported, trying anyway

esphome/device_packages/sensor-box-diy.yaml

@@ -8,16 +8,14 @@ light:
     num_leds: 5
     type : GRB
     name: "${friendly_devicename} PM25"
-    effects: !include
+    effects: *shared_effects
-      - file: ../partials/effects.yaml
   - platform: neopixelbus
     variant: WS2812
     pin: D3
     num_leds: 5
     type : GRB
     name: "${friendly_devicename} PM10"
-    effects: !include
+    effects: *shared_effects
-      - file: ../partials/effects.yaml
   - platform: binary
     name: "${friendly_devicename} Lamp"
     output: relay

esphome/partials/effects.yaml

@@ -1,38 +1,39 @@
-- strobe:
+light: &shared_effects
-- flicker:
+  - strobe:
-- addressable_rainbow:
+  - flicker:
-- addressable_color_wipe:
+  - addressable_rainbow:
-- addressable_scan:
+  - addressable_color_wipe:
-- addressable_twinkle:
+  - addressable_scan:
-- addressable_random_twinkle:
+  - addressable_twinkle:
-- addressable_fireworks:
+  - addressable_random_twinkle:
-- addressable_flicker:
+  - addressable_fireworks:
-- addressable_color_wipe:
+  - addressable_flicker:
-      name: Kingsday
+  - addressable_color_wipe:
-      colors:
+        name: Kingsday
-        - red: 78%
+        colors:
-          green: 6%
+          - red: 78%
-          blue: 18%
+            green: 6%
-          num_leds: 2
+            blue: 18%
-        - red: 100%
+            num_leds: 2
-          green: 100%
+          - red: 100%
-          blue: 100%
+            green: 100%
-          num_leds: 2
+            blue: 100%
-        - red: 0%
+            num_leds: 2
-          green: 24%
+          - red: 0%
-          blue: 65%
+            green: 24%
-          num_leds: 2
+            blue: 65%
-        - red: 100%
+            num_leds: 2
-          green: 61%
+          - red: 100%
-          blue: 0%
+            green: 61%
-          num_leds: 6
+            blue: 0%
-      add_led_interval: 100ms
+            num_leds: 6
-      reverse: true
+        add_led_interval: 100ms
-- random:
+        reverse: true
-    name: "My Slow Random Effect"
+  - random:
-    transition_length: 30s
+      name: "My Slow Random Effect"
-    update_interval: 30s
+      transition_length: 30s
-- random:
+      update_interval: 30s
-    name: "My Fast Random Effect"
+  - random:
-    transition_length: 4s
+      name: "My Fast Random Effect"
-    update_interval: 5s
+      transition_length: 4s
+      update_interval: 5s