mtrudel337 , two "system" databases of SSRS, with default names ReportServer and ReportServerTempDB can be hosted on Azure SQL Managed Instance as long as SSRS 2017 or newer SSRS release is used. That's the main topic of this blog post, as its title suggests.
I can confirm that Azure SQL Database (another PaaS service from the Azure SQL family) cannot host two "system" databases of SSRS, regardless of SSRS release.
SSRS as a stateless report server (not talking about its two system databases here) cannot be hosted on Azure SQL Managed Instance. That's what Azure VM is needed for, if you want to move your on-prem SSRS installation to Azure. SSRS hosted on Azure VM can connect for reporting purposes to any user databases hosted in Azure SQL Database or Azure SQL Managed Instance, as long as there is connectivity established between the two, and SQL authentication used.
I hope this clarification helps, and I am more than happy to make it more clear in the article itself if you see opportunity for improvement there.
Thanks.