You have to configure  your postgreSQL Database :-

To configure follow this link:- https://www.odoo.yenthevg.com/connecting-powerbi-odoo/

For Excel:-

In Excel the best way is to use ODBC (or Live Data Connector). ODBC can connect your apps to Excel, passing real-time data from your app to Excel. As data is updated in your app, your Excel dashboard will also be updated to reflect the latest information. This is a perfect option if you track and store data in another place, and prefer creating a dashboard in Excel. Data can be imported two different ways: in a flat file or a pivot table. 

Refer this link :- https://www.smartsheet.com/how-create-dashboard-excel

Thanks to all.

So, I could conclude that it is not possible (or not so easy) to create my own dashboard in excel without using the exporting function... The Odoo dashboards are easy to use coupled with search filters, but unfortunately, you cannot view some of them at the same time.

Hello Piero,

I think You have to use XML-RPC Services.

https://doc.odoo.com/v6.0/developer/6_22_XML-RPC_web_services/index.html