Is SQL Server on Linux supported?

Yes, SQL Server on Linux and in containers are supported with the following limitations:

No capacity handling (and thereby no forecasting)
No failover information
It is not possible to determine if the Linux host running the SQL Server is physical or virtual. This has to be manually set in the Performance Store Control Center
The SQL Server Patch Manager is only supported on Windows platforms
The SQL Server log directory will not be shared

Note, when adding a SQL Server hosted on a Linux platform in the Performance Store Control Center, the SQL Server should be added with the port number, e.g. ubuntu2,1433