Nesting blocks inside a structure

Ah, figured it out as per this thread: How to enable table block? - #3 by toddz

I was missing “snippets/blocks/table.php” in my snippets folder.

Snippet (snippets/blocks/table.php)

<?php 
$rows = $block->rows()->toStructure();
if($rows):
?>
<table class="table">
    <tr>
        <th>This snippet is linked!</th>
    </tr>
    <?php foreach($rows as $row): ?>
        <tr>
        <td><?= $row->name()->html() ?></td>
        <td><?= $row->role()->html() ?></td>
        <td><?= $row->year()->html() ?></td>
        </tr>
    <?php endforeach ?>
</table>
<?php endif ?>

Plugin (plugins/section-block/snippets/blocks/sections.php)

<div class="row <?= $block->title()->lower() ?>">
  <div class="title">
    <h2><?= $block->title() ?></h2>
  </div>
  <div class="blocks">
    <?= $block->sectionBlocks()->toBlocks() ?>
  </div>
</div>

Blueprint (blueprint/blocks/section.yml)

name: Section
icon: add
fields:
  title:
    type: text
    required: true
  sectionBlocks:
    label: Blocks
    type: blocks
    fieldsets:
      - heading
      - text
      - image
      - list
      - table

Blueprint (blueprint/blocks/table.yml)

name: People
icon: menu
preview: table
fields:
  rows:
    type: structure
    columns:
      name:
        width: 1/3
      role:
        width: 1/3
      year:
        width: 1/3
        align: right
    fields:
      name:
        type: text
        width: 1/3
      role:
        type: text
        width: 1/3
      year:
        type: number
        width: 1/3
        align: right

Hope this helps!