You cannot use the license of an Azure SQL Managed Instance to install SQL Server 2019 Reporting Services (SSRS) on an Azure SQL VM. The licensing for SQL Managed Instance and SQL Server on Azure VMs are separate and not interchangeable.
For SSRS on an Azure SQL VM, you would need to use a separate SQL Server license. You can either:
- Use a Pay-As-You-Go License.
- Use Azure Hybrid Benefit: If you have existing SQL Server licenses with Software Assurance, you can use these licenses on Azure VM.