Hi @jmsimonramos1,

• You create data_users_1 group.
• You grant data_users_1 the needed privileges to my_catalog_1: 

GRANT ALL PRIVILEGES ON CATALOG my_catalog_1 to `data_access_1`;​

• You create data_users_2 group.
• You grant data_users_2 the needed privileges to my_catalog_2:

GRANT ALL PRIVILEGES ON CATALOG my_catalog_2 to `data_access_2`;​​

• data_users_1 has now all privileges on my_catalog_1, whereas data_users_2 has now all privileges on my_catalog_2
• There is no need to limit catalog visibility on the workspace level if there is no requirement to do so.
• Check the docs on unity catalog privilege management