Sample code to create a Vue 3 web component.

vue3-webcomponent-main.js

import { createApp, h } from 'vue'; // import components from Vue 3
import App from './App.vue';

// importing vue 3 web component wrapper
// https://www.npmjs.com/package/vue3-webcomponent-wrapper
import wrapper from "vue3-webcomponent-wrapper"; 

// This line will mount our component to the dom. This is only used in local development.
// but it is not necessary for the webcomponent wrapper to work.
// You can comment this out
createApp(App).mount('#app');

const CustomElement = wrapper(App, createApp, h)

// registering our component as 'my-custom-element' 
// once build, we can simply load our component in the dom.
window.customElements.define('my-custom-element', CustomElement);