Appstore connect API client method to get prices from group ID and provider ID (which are provided by Appstore server API subscriptionStatuses's response).

AppstoreConnectClient.php

<?php

class AppStoreConnectAPIClient
{
    ...

    /**
     * Return all prices indexed by currency code, given a subscription group ID and a product ID.
     * @return array<int|string, array<string,mixed>>
     */
    public function pricesByGroupAndProductID(string $groupID, string $productID): array
    {
        //get subscription ID
        $subscriptions = $this->subscriptionsByGroup($groupID);

        $subscription = array_filter((array)$subscriptions->data, function ($e) use ($productID) {
            return $e->attributes->productId === $productID;
        });

        if (empty($subscription)) {
            $this->logger->error('Appstore subscription identifier not found', compact('groupID', 'productID'));
            throw new AppStoreClientException('Appstore subscription identifier not found');
        }

        $subscriptionID = reset($subscription)->id;

        //get all pricing and territory info that subscription ID
        $url = "v1/subscriptions/{$subscriptionID}/prices?limit=200&include=subscriptionPricePoint,territory";
        $data = [];
        $included = [];
        $nextPageCursor = '';

        while (!is_null($nextPageCursor)) {
            $response = $this->request($url . ($nextPageCursor ?  '&cursor=' . $nextPageCursor : ''), 'GET');
            array_push($data, ...$response->data);
            array_push($included, ...$response->included);

            $nextPageUrl = property_exists($response->links, 'next')
                ? AnyUrl::fromText($response->links->next)
                : null;
            if (is_null($nextPageUrl)) {
                $nextPageCursor = null;
            } else {
                parse_str($nextPageUrl->query(), $queryParams);
                $nextPageCursor = is_string($queryParams['cursor']) ? $queryParams['cursor'] : null;
            }
        }

        //split and reindex price points and territories
        $pricePoints = [];
        $territories = [];
        foreach ($included as $pricePointOrTerritory) {
            if ($pricePointOrTerritory->type === 'subscriptionPricePoints') {
                $pricePoints[$pricePointOrTerritory->id] = $pricePointOrTerritory->attributes;
            } elseif ($pricePointOrTerritory->type === 'territories') {
                $territories[$pricePointOrTerritory->id] = $pricePointOrTerritory->attributes;
            }
        }

        //build prices by country
        $pricesByCountry = [];
        foreach ($data as $priceRef) {
            $pricePointID = $priceRef->relationships->subscriptionPricePoint->data->id;
            $territoryID = $priceRef->relationships->territory->data->id;

            $pricesByCountry[$territoryID] = array_merge(
                (array)$pricePoints[$pricePointID],
                (array)$territories[$territoryID]
            );
        }

        return $pricesByCountry;
    }

    ...
}

response.json

{
  "pricesByGroupAndProductID": {
    "ARE": {
      "customerPrice": "699.99",
      "proceeds": "566.66",
      "proceedsYear2": "566.66",
      "currency": "AED"
    },
    "AFG": {
      "customerPrice": "179.0",
      "proceeds": "152.15",
      "proceedsYear2": "152.15",
      "currency": "USD"
    },
    "ATG": {
      "customerPrice": "179.0",
      "proceeds": "152.15",
      "proceedsYear2": "152.15",
      "currency": "USD"
    },
    "AIA": {
      "customerPrice": "179.0",
      "proceeds": "152.15",
      "proceedsYear2": "152.15",
      "currency": "USD"
    },
    "ALB": {
      "customerPrice": "199.0",
      "proceeds": "140.96",
      "proceedsYear2": "140.96",
      "currency": "USD"
    },
    "ARM": {
      "customerPrice": "199.0",
      "proceeds": "140.96",
      "proceedsYear2": "140.96",
      "currency": "USD"
    },
    "AGO": {
      "customerPrice": "179.0",
      "proceeds": "152.15",
      "proceedsYear2": "152.15",
      "currency": "USD"
    },
    "ARG": {
      "customerPrice": "179.0",
      "proceeds": "152.15",
      "proceedsYear2": "152.15",
      "currency": "USD"
    },

    ...
}