This command, can be run on both the primary and secondary node.

SELECT local_database_name
 ,role_desc
 ,internal_state_desc
 ,transfer_rate_bytes_per_second
 ,transferred_size_bytes
 ,database_size_bytes
 ,start_time_utc
 ,end_time_utc
 ,estimate_time_complete_utc
 ,total_disk_io_wait_time_ms
 ,total_network_wait_time_ms
 ,is_compression_enabled
FROM sys.dm_hadr_physical_seeding_stats