Magento 2 - Call list phtml by passing collection variable

First you need to create block Vendor\Module\Block\ProductList.php by overriding this function _getProductCollection() by extending your class from this Magento\Catalog\Block\Product\ListProduct.

protected function _getProductCollection()
{   
        /* Do whatever you want to do with your collection */  

        $this->_productCollection = $yourcollection;
        return $this->_productCollection;
}

Now you can call your ptml file. Your collection has been passed to that phtml

$block = $viewBlock->getLayout()
                ->createBlock('Vendor\Module\Block\ProductList')
                ->setTemplate('Magento_Catalog::product/list.phtml')
                ->toHtml();

I hope this will help others

try this way....

   $block = $viewBlock->getLayout()
                    ->createBlock('Vendor\Module\Block\ProductList')
                    ->setCustomvalue('111111')
                    ->setTemplate('Magento_Catalog::product/list.phtml')
                    ->toHtml();

and you can get value

$block->getCustomvalue();

Your $block variable contains the content of list.phtml so here you just have called it.

That list.phtml contains $_productCollection that it gets it from the module block, in your $block you can do anything in that collection because the collection has already been loaded, it's too late to update it at this level.

What you can to do is to rewrite that block Magento_Catalog\Block\Product\ListProduct.php and after that, you can update the collection.