place each one of the databases that the SQL Server contains. with the Reader ROLE get all the databases on the Server.
Seems you haven't understand in any way how "Azure SQL Database" works.
You don't get a server, you get one database.
Every database is a separate unit with separate user and separat permissions, if you have many "Azure SQL Database" then the is no relation between, beside your subscription.
No way to get what you are looking for.