Sql-server – Can CDC or Change Tracking be against a read only secondary

If you need bidirectional synchronization, have a look at merge replication. (Good introduction: http://www.sqlservercentral.com/stairway/72401/)

However, you question sounds like you don't want those changes to be applied to the master sales database. In that case I would setup shadow tables that take the changes and use replication to load the master tables. The logic to write to the shadow tables and read from the shadow tables if there is a row, form the master table otherwise could be placed in a view with an instead-of trigger. The following is a conceptual example of that model:

create table dbo.product-master(Id int, ...);
create table dbo.product-shadow(Id int,....);
GO
CREATE VIEW dbo.product
AS
SELECT m.Id,
       CASE WHEN s.ID is NULL THEN m.col1 ELSE s.col1 END AS col1, --show shadow row if it exists, master row otherwise
       CASE WHEN s.ID is NULL THEN m.col2 ELSE s.col2 END AS col2,
       CASE WHEN s.ID is NULL THEN m.col2 ELSE s.col3 END AS col3
FROM dbo.product-master m
LEFT JOIN dbo.product-shadow s
ON m.Id = s.Id;
GO
CREATE TRIGGER dbo.product-IUD INSTEADOF INSERT,UPDATE,DELETE
AS
BEGIN
  --use INSERTED and DELETED virtual tables and the MERGE statement to apply changes to the shadow table
END;
GO

To load the master tables you could use any kind of replication (see link above for an introduction).

Change Tracking and Change Data Capture are, while having similar goals, actually separate features. For AlwaysOn Availability groups, the limitations indicate that you can't use the synchronous Change Tracking feature at all, though the asynchronous Change Data Capture is possible to enable: It's just not a feature Microsoft will support for Active Secondaries.

Generally, things like that aren't supported because there exists a supported way to do so. In this case, enabling CDC on the primary node of an AlwaysOn Availability Group is completely supported, allowing the captured changes to be replicated along to the Active Secondaries, so would likely be the path you should explore for your SSIS needs on the secondaries.

You can read more about the differences between Change Tracking and Change Data Capture here, and more about setting up CDC on the primary replica here.