From dotnet/efcore#7152 (comment):
That walkthrough needs some love because it makes no mention about the need for the dummy console project and makes no mention of getting started with how migrations will work specifically in a Xamarin project. ... The need for a separate console project and how to use it just isn't there. I'd suggest updating the walkthrough document to include this information.
We mention it here but never really show how to do it.
From dotnet/efcore#7152 (comment):
We mention it here but never really show how to do it.