Purview Data Governance: Grant access to business consumers search Unified Catalog "Data products"

If you grant any user the local catalog reader on a Governance Domain, no other users than users with local catalog reader permissions on that specific Governance Domain will be able to see anything in that domain.

My advice: Delete all local catalog reader permissions on all Governance Domains, only grant Global Catalog Reader permissions (this permissions can be found in 'settings'). 

Now every user with global catalog reader permissions will be able to see every dataproduct. Want to make a Governance Domain and it's data products invisible to others again? Only then you should apply local catalog reader permissions again to that specific domain.

In my organization we have 0 Governance Domains that are secret. Anyone is allowed to know, at least on metadata level, what data others domain have.