Query to show the Bits that comprise a VARCHAR2 value

I'm running Oracle Enterprise DB 19c. I'm having an issue with client/DB charsets and encoding. In short, I need to validate the data in an VARCHAR2  column in a table to see that it is valid. The data is a string/VARCHAR2 at the DB end. We have had issues where the Irish Fada has been written to the DB by one client but when retrieved is displayed as another character.

Due to the various client local and NLS_LANG settings the easiest way to do this would be to retrieve this string and list the bits that comprise it as simply viewing it means I need to check all the client local/NLS_LANG settings.