Edit in JSFiddle

const svgText = `<svg style="width:48px;height:48px" viewBox="0 0 24 24">
<path fill="currentColor" d="M18.5,4L19.66,8.35L18.7,8.61C18.25,7.74 17.79,6.87 17.26,6.43C16.73,6 16.11,6 15.5,6H13V16.5C13,17 13,17.5 13.33,17.75C13.67,18 14.33,18 15,18V19H9V18C9.67,18 10.33,18 10.67,17.75C11,17.5 11,17 11,16.5V6H8.5C7.89,6 7.27,6 6.74,6.43C6.21,6.87 5.75,7.74 5.3,8.61L4.34,8.35L5.5,4H18.5Z" />
</svg>`;
const svgLink = `<svg style="width:48px;height:48px" viewBox="0 0 24 24">
<path fill="currentColor" d="M3.9,12C3.9,10.29 5.29,8.9 7,8.9H11V7H7A5,5 0 0,0 2,12A5,5 0 0,0 7,17H11V15.1H7C5.29,15.1 3.9,13.71 3.9,12M8,13H16V11H8V13M17,7H13V8.9H17C18.71,8.9 20.1,10.29 20.1,12C20.1,13.71 18.71,15.1 17,15.1H13V17H17A5,5 0 0,0 22,12A5,5 0 0,0 17,7Z" />
</svg>`;
const svgImage = `<svg style="width:48px;height:48px" viewBox="0 0 24 24">
<path fill="currentColor" d="M8.5,13.5L11,16.5L14.5,12L19,18H5M21,19V5C21,3.89 20.1,3 19,3H5A2,2 0 0,0 3,5V19A2,2 0 0,0 5,21H19A2,2 0 0,0 21,19Z" />
</svg>`;

const blocks = [
  {
    id: 'text',
    label: 'Text',
    category: 'Basic',
    media: svgText,
    activate: true,
    content: {
      type: 'text',
      content: 'Insert your text here',
      style: { padding: '10px' },
    }
  },{
    id: 'link',
    label: 'Link',
    category: 'Basic',
    media: svgLink,
    activate: true,
    content: {
      type: 'link',
      content: 'Insert your link here',
      style: { color: '#d983a6' }
    }
  }, {
    id: 'image',
    label: 'Image',
    category: 'Basic',
    media: svgImage,
    activate: true,
    content: { type: 'image' }
  }
];

const editor = grapesjs.init({
  container: '#gjs',
  fromElement: true,
  height: '100%',
  storageManager: false,
  noticeOnUnload: false,
  blockManager: {
    custom: true,
    blocks,
  },
});

// Open the default Block Manager container
const { Panels } = editor;
Panels.getButton('views', 'open-sm').set('active', false);
Panels.getButton('views', 'open-blocks').set('active', true);

// Load the Vue app
const app = new Vue({
  el: '.blocks-wrp',
  data: { blocks: [] },
  mounted() {
    editor.on('block:custom', this.handleBlocks);
  },
  destroyed() {
    editor.off('block:custom', this.handleBlocks);
  },
  methods: {
    handleBlocks(props) {
      this.blocks = props.blocks;
      this.dragStart = props.dragStart;
      this.dragStop = props.dragStop;
      // Move inside the default container if exists
      const cnt = props.container;
      cnt && cnt.appendChild(this.$el);
    },
    onDragStart(block) {
      this.dragStart(block);
    },
    onDragStop() {
      this.dragStop();
    },
  }
});

<div id="gjs">
  <div style="padding: 25px">Custom Block Manager</div>
</div>

<div style="display: none;">
  <!-- Vue app  -->
  <div class="blocks-wrp">
    Custom Blocks
    <div class="blocks">
      <div v-for="block in blocks" class="block" :key="block.getId()" 
        @dragstart="onDragStart(block)" @dragend="onDragStop()" draggable>
        <div class="block-media" v-html="block.getMedia()"></div>
        <div class="block-label">{{ block.getLabel() }}</div>
        <div class="block-cat">CAT: {{ block.getCategoryLabel() }}</div>
      </div>
    </div>
  </div>
</div>

body, html {
  margin: 0;
  height: 100%;
}

.block {
  user-select: none;
  min-width: 45px;
  padding: 1em;
  box-sizing: border-box;
  min-height: 90px;
  cursor: all-scroll;
  text-align: center;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  border: 1px solid rgba(0,0,0,.2);
  border-radius: 3px;
  margin: 10px 2.5% 5px;
  box-shadow: 0 1px 0 0 rgb(0 0 0 / 15%);
  transition: all .2s ease 0s;
  transition-property: color;
}

.block:hover {
  color: #d278c9;
}