No. A read receipt, a delivery result, and acceptance of your send request are different evidence. Do not convert the absence of a read event into a failed-delivery result or assume that a customer has seen the message.
Check the delivery status and whether your webhook subscriptions include the relevant status events. If the message has an explicit failure, use that reason. If status events are missing despite a confirmed subscription and working receiver, report the message reference and times to support. Avoid resending merely to obtain a read receipt.