Well Nokia is a joke. I originally setup my phone without a sim card in and in and could not update to Oreo. I reset my Nokia 8 and setup my Nokia 8 with sim card in and still no Oreo.
This was Nokia care response also
"In order to receive regular updates on your mobile device, you will need the proper provisioning to do so, if a SIM card has been inserted. Whenever you insert a SIM card into your device for the first time, it will automatically try to install the provisioning, which is provided by the relevant Network provider for that SIM card. If they did not update this provisioning to include our OTA update server, you will not be able to receive these updates, like some other Nokia 8 users might have done.
The best way to make sure your device is up to date would be to have it search for updates, without it having any SIM card inserted into it previously - hence no SIM network settings pre-installed on the device - and connecting via Wi-Fi. If you had inserted a SIM card previously and that SIM card does not have the correct provisioning in order to receive the latest update, you would have to perform a Factory settings reset of the device and try to update again without inserting the SIM card.
(Please note that SIM card provisioning affects any kind of wireless network connection, including Wi-Fi networks)
It is very regrettable to hear about your decision to return your Nokia 8 device"
Still no Oreo even after the useless response. This is why I think I'm returning to oneplus