Will Barman support restore of single database?

This feature allows only selected databases to be restored. Databases not specifically included will be restored as sparse, zeroed files to save space but still allow PostgreSQL to perform recovery. After recovery, the databases that were not included will not be accessible but can be removed with the drop database command.
 

The --db-include option can be passed multiple times to specify more than one database to include.

See Restore Selected Databases for additional information and caveats.