Create a SQL user on Azure SQL Managed instance after database creation using automation system (Terraform, ARM deployment or bicep)

Using Terraform (or other automation process using Az), I have created an Azure SQL managed instance but I don't have a solution to create a user (different from administrator) that gives acess to the databases.

So after SQL instance creation, I can also create my two SQL databases using Terraform.

These three resources (Instance + 2 DB) are created using SQL managed instance administrator user permissions.

I now want to create and assign a user on each database but it seems is not permitted by the Az command (so Terraform Azure RM provider don't provide this feature)

Note that the process that deploy the Azure Managed instance have only the acess to Azure using Az module. (no direct access to the SQL Managed instance deployed)

Example :

User 1 have only access to DB1

User 2 have only access to DB2

So, the question is, how can I create the user Sql to access database in my automatic process.

I can't connect the DB and run the SQL script directly as my Azure SQL server managed instance is not exposed on internet.

These actions must be made by an automatic process so can't have manual actions from a user.