I am trying the new Entity Framework Core with MySQL Connector.
I can get a valid DbContext and write into the database so everything has been setup correc
The Microsoft.EntityFrameworkCore.Relational (https://www.nuget.org/packages/Microsoft.EntityFrameworkCore.Relational/) package provides extension methods for this - you can use dbContext.Database.OpenConnection() or dbContext.Database.GetDbConnection() to get the DbConnection object.
Note: if you have Microsoft.EntityFrameworkCore.SqlServer installed then you don't have to explicitly install this package