How does SQL Server maintain rowcount metadata?

For an example rowstore table... CREATE TABLE T(Id INT PRIMARY KEY, C1 INT NULL, C2 INT NULL); There are a variety of different methods of retrieving table row counts from metadata in SQL Server - such as the below

SELECT SUM(rows) 
FROM sys.partitions
WHERE object_id = object_id('dbo.T') AND index_id <= 1;

SELECT SUM(row_count) 
FROM sys.dm_db_partition_stats
WHERE object_id = object_id('dbo.T') AND index_id <= 1;

SELECT SUM(rows)
FROM sys.sysindexes
WHERE id = object_id('dbo.T') AND indid <= 1;

SELECT OBJECTPROPERTYEX(object_id('dbo.T'), 'Cardinality')

The execution plans apparently show a variety of different objects being used - such as the below. * sysrowsets OUTER APPLY OpenRowset(TABLE ALUCOUNT * sysidxstats CROSS APPLY OpenRowSet(TABLE PARTITIONCOUNTS * sysidxstats i CROSS APPLY OpenRowSet(TABLE INDEXPROP What is going on here? Does SQL Server really maintain this metadata in multiple places? If so which is the most reliable method?