Unpleasant but works

app/frontend/application.js

@@ -12,13 +12,9 @@ import "custom-event-polyfill"
 import "intersection-observer"
 //
 
-// Import GOV.UK Frontend
-import GOVUKFrontend from 'govuk-frontend'
-
-// Import GOV.UK Prototype Components
-import GOVUKPrototypeComponents from 'govuk-prototype-components'
-
 require.context("govuk-frontend/govuk/assets")
+import GOVUKFrontend from "govuk-frontend"
+import GOVUKPrototypeComponents from "govuk-prototype-components"
 import "./styles/application.scss"
 import "./controllers"
 

app/frontend/controllers/govukfrontend_controller.js

@@ -1,8 +1,10 @@
-import { initAll } from "govuk-frontend";
+import GOVUKFrontend from "govuk-frontend";
+import GOVUKPrototypeComponents from "govuk-prototype-components"
 import { Controller } from "@hotwired/stimulus";
 
 export default class extends Controller {
   connect() {
-    initAll()
+    GOVUKFrontend.initAll()
+    GOVUKPrototypeComponents.initAll()
   }
 }

app/frontend/styles/application.scss

@@ -10,11 +10,8 @@ $govuk-font-url-function: frontend-font-url;
 $govuk-image-url-function: frontend-image-url;
 $govuk-global-styles: true;
 
-// Import GOV.UK Frontend
-@import "govuk-frontend/govuk/all";
-
-// Import GOV.UK Prototype Components
-// @import "govuk-prototype-components/x-govuk/all";
+@import "node_modules/govuk-frontend/govuk/all";
+@import "node_modules/govuk-prototype-components/x-govuk/all";
 
 @import "accessible-autocomplete";
 @import "button";

webpack.config.js

@@ -43,7 +43,7 @@ module.exports = {
     ],
   },
   resolve: {
-    modules: ['node_modules', 'node_modules/govuk-frontend/govuk', 'node_modules/govuk-prototype-components/x-govuk']
+    modules: ['node_modules', 'node_modules/govuk-frontend/govuk']
   },
   output: {
     filename: "[name].js",