According to the EF Provider Support page (on 12/06/2018), in the "Future Provider" section:
The Oracle .NET team announced that it wants to release a provider for EF Core 2.0 in the third quarter of 2018. See the direction statements for .NET Core and Oracle's Entity Framework Core for more information. Forward any doubts about this provider, including the timeline of launch, to the Oracle Community Website.
And you have this in NugGet
: link