Magento 2 Get Tier Price of Group while user not logged in - magento2

Question

I try to get a tier price for a certain customer group in Magento 2.
The tier price should be shown on webshop even if a user is not logged in (and thus not a member of the group at that time)
This tier price is for members only. But to encourage visitors to become a member, the member price and the regular (final) must be visible.
I'm overwriting Magento\Framework\Pricing\Render\RendererPool.
I can get the minimal Tier Price for a configurable product with this group like this:
private function getMemberPrice(Product $product)
{
if ($product->getTypeId() == 'configurable') {
$om = \Magento\Framework\App\ObjectManager::getInstance();
$configurable = $om->get('Magento\ConfigurableProduct\Model\Product\Type\Configurable');
$children = $configurable->getUsedProducts($product);
/**
* #var $childKey
* #var Product $child
*/
$minimalTierMemberPrice = null;
foreach ($children as $childKey => $child) {
$tier_prices = $child->getTierPrices();
if ($tier_prices && count($tier_prices) > 0) {
foreach ($tier_prices as $tier_price) {
if ($tier_price->getCustomerGroupId() == 4 /* MEMBER CUSTOMER GROUP ID */) {
if (!$minimalTierMemberPrice || $minimalTierMemberPrice->getValue() > $tier_price->getValue()) {
$minimalTierMemberPrice = $tier_price;
}
}
}
}
}
if ($minimalTierMemberPrice) {
return $minimalTierMemberPrice;
} else {
return $this->getNonMemberPrice($product);
}
}
//if none member price was set, return the memberprice
return $this->getNonMemberPrice($product);
}
After that I try to override createPriceRender to generate the block with template.
I try to wrap my head around for several days now. That's why I'm trying to push my minimal tier price in the FinalPriceBox / final_price.phtml template as in this code:
public function createPriceRender(
$priceCode,
SaleableInterface $saleableItem,
array $data = []
)
{
if (isset($data['special_price']) && $data['special_price'] == 'member_price') {
$renderClassName = FinalPriceBox::class;
$blockTemplate = 'Magento_Catalog::product/price/final_price.phtml';
$product = $this->getProduct($saleableItem->getId());
$price = $this->getMemberPrice($product);
//$price = $saleableItem->getPriceInfo()->getPrice($priceCode);
//$price = $product->getPriceInfo()->getPrice('final_price');
$arguments['data'] = $data;
$arguments['rendererPool'] = $this;
$arguments['price'] = $price;
$arguments['saleableItem'] = $saleableItem;
//$arguments['member_price'] = true;
/** #var \Magento\Framework\View\Element\Template $renderBlock */
$renderBlock = $this->getLayout()->createBlock($renderClassName, '', $arguments);
if (!$renderBlock instanceof PriceBoxRenderInterface) {
throw new \InvalidArgumentException(
'Block "' . $renderClassName . '" must implement \Magento\Framework\Pricing\Render\PriceBoxRenderInterface'
);
}
$renderBlock->setTemplate($blockTemplate);
return $renderBlock;
} else {
//original code here
return parent::createPriceRender($priceCode, $saleableItem, $data);
}
}
I get following error when I try this
Fatal error: Uncaught TypeError: Argument 3 passed to Magento\Catalog\Pricing\Render\FinalPriceBox\Interceptor::__construct() must implement interface Magento\Framework\Pricing\Price\PriceInterface, instance of Magento\Catalog\Model\Product\TierPrice given
It's quite clear what's the error about. But anyway I want to get my tier price, but with the priceinterface implemented (as the original Rendererpool gets for final prices etc.)
Should I get my tier prices in another way?