How can I add a wrapper class to individual blocks inside of an InnerBlocks component?

Ok so I don’t feel very good about this solution, but – using the render_block hook:

1. conditional to find the custom block
2. set the $block_content variable=””; to clear it (or if you want to nest something inside tags, you can try to explode $block_content)
3. loop through each child block and pull out the innerHTML, append to the $block_content variable and return that

function gss_block_wrapper($block_content, $block)
{
        if ($block['blockName'] === 'create-block/gutenberg-swiper-slider') {
            $block_content="";
            foreach ($block['innerBlocks'] as $innerblock) {
                $innerHTML = $innerblock['innerHTML'];
                //innerHTML of each child block
                $content="<div class="swiper-slide">" .  $innerHTML . '</div>';
                $block_content .= $content;
            }
        }
    return $block_content;
}

add_filter('render_block', 'gss_block_wrapper', 10, 2);

Maybe I’m just not doing gutenberg right, but it feels like the InnerBlocks component could do with a built-in way to wrap child blocks.