What user/password credentials I am supposed to enter within 3rd party applications such as DataHub/Amundsen/OpenMetadata when we are using Google SSO?
Sorry, I didn't get the question. If you're trying to access a service like those from within Metabase, unless those services support any connector like the ones we have, it won't be possible. Another option for you is to build something that can export data from those services to a postgres or any other DW and then make Metabase connect to those.
Metabase does not support OAuth2 to connect to databases
I want to include Metabase objects within data governance tools such as DataHub, Amundsen, OpenMetadata and so on. These tools of course do have connectors to Metabase, but I have to input Metabase user and password so these tools can connect to the Metabase. The question is what credentials I am suppose to use when we have enable Google SSO, meaning users authenticate using Google to access Metabase.