Hello Rabhia,
Your sample was perfect! Using the LayoutInflater to load an existing layout and then set the content of the SfNavigationDrawer is working!
I have already used the same technique to an existing project of mine, all is working as expected!
LayoutInflater inflater = LayoutInflater.From(this); // 1
View InflatedContentView = inflater.Inflate(Resource.Layout.ContentLayout1, null);
drawer.DrawerContentView = InflatedDrawerView;
Thank you very much for the quick and correct response!