Good morning, we must have patience.
As was written several times by blackview_admin, the update from nougat to oreo would have arrived between 6 months and 1 year. You will see that what is promised will be done.
In the meantime I have successfully used this unofficial version for a few months:http://4pda.ru/forum/index.php?s=&showt ... p=79200694
We just have to wait for the official update.