Manage security alerts in Microsoft 365 security center(MTP), Sentinel or separately?

luizao_lf The main reason to have the other Azure security alerts also show up in Azure Sentinel is to have a single pane of glass to see all the issues in your environment.  You will still go back to the other systems to perform the investigations since they have the tools to do that.

AFAIK, there is no way to have the Azure Sentinel alerts show up in MTP.

Overall, it is better to use the products that own the logs to perform the investigations since they are made to perform that task. So if an alert shows up in MCAS, you can have it show up in Azure Sentinel just to have one less place to look, but you will need to go back into MCAS to do the investigations.  Even if you do have the same logs in Azure Sentinel, you would need to re-invent the wheel in order to do what the other systems already can do.