If the page uses a production/minified build of Vue.js, devtools inspection is disabled by default so the Vue pane won't show up. To make it work for pages opened via file:// protocol, you need to ...

vue-devtools-legacy/ ├── extracted_plugin/ # Source code of the extension │ ├── manifest.json # Chrome extension manifest │ ├── package.json # Node.js package configuration │ ├── devtools.html # ...