I'm currently facing this issue when testing my InApp subscription in a different device (different country, iphone 17 PM, ios 26), the Subscription Products are not being displayed.

I have tested the subscription and it is working fine on Development IPA's (shared through Diawi), IPA's Distributed through Testflight as Internal Testers.
Currently the issue was being faced on this particular Tester, who is added as an external tester in testflight.

I have Agreed to all Paid app agreements, added all bussiness Details.
I have set the subscription product availability to all Region
Inapp Subscription products are under Ready to Submit stage Product Listing
Subscription Group Localization is under Prepare for Submission stage Locale
The Subscription price has a valid value for the country in which the issue is occuring
I have not yet submitted the app to review.
This is the function which fetches the Inapp Products.

 Future initializeInAppPurchase() async {
    _isPurchaseTapped = false;

    _isPurchaseSuccessShown = false;
    try {
      _subscription ??= _iap.purchaseStream.listen(
        _listenToPurchaseUpdated,
        onDone: () async {
          await _subscription?.cancel();
        },
        onError: (error) async {
          await _subscription?.cancel();
        },
      );

      final available = await _iap.isAvailable();
      isAvailable.value = available;

      if (!available) {
        return;
      }

      final response = await _iap.queryProductDetails(_productIds);

      if (response.error != null) {
        log('IAP query error: ${response.error}');

        return;
      }

      products.assignAll(
        response.productDetails.where(
          (productDetail) => productDetail.rawPrice > 0,
        ),
      );

      await fetchUserSubscription();
    } catch (e) {
      log(e.toString());
    } finally {
      _isLoading.value = false;
    }
  }