Manage SCD 2 table using the INSERT --- ON CONFLICT

Hello,

I am trying to use the INSERT ON CONFLICT syntax to build an SCD 2 table
loader.

here are the behaviors I need to achieve:
SCD 2 table: TAB_OUT
new candidate records: TAB_IN

The table TAB_IN contains the new candidate records to be submitted to
TAB_OUT.
*Case 1*: The record presented by TAB_IN is already present in TAB_OUT and
the fields were not modified
-> DO NOTHING

*Case 2*: The record presented by TAB_IN is not present in TAB_OUT
-> INSERT NEW RECORD (*OK*)

*Case 3*: The record presented by TAB_IN is already presente in TAB_OUT and
the fields were modified
-> CLOSE existing record in TAB_OUT(*OK*)
-> *INSERT new RECORD (KO)*

I can't find a way to retrieve the list of records that were updated ON
CONFLICT. I have tried the RETURNING but, it is retrieving the list of
records processed either in the INSERT or the UPDATE.

Am I missing something or it is not possible with this syntax?

Thanks in advance

Johann