Since your issue is about Project online, and our forum focus on SharePoint. I wil recommend you to raise a new ticket on Microsoft TechCommunity. This is a Microsoft forum dedicated to discussing Project. You might get some more professional advice there. Thanks for your understanding.
Project online sharepoint.com - Registered app security for api consumation (sécurité consommation api)

I need the security ("Permission Request XML" in appinv) in sharepoint.com for a registered app can access a project online api (https://mysite.sharepoint.com/sites/pwa/_api/projectdata)..)
A c# application will consume the api data by using the registered app.
j'aurais besoin de la sécurité ("Permission Request XML" dans appinv) sharepoint.com pour qu'une application enregistré (RegisteredApps) puisse accéder à un api project online. (https://mysite.sharepoint.com/sites/pwa/_api/projectdata).
Une application c# pourra ensuite consommer les données de l'api en utilisant l'application enregistré.
Note I tried to ask on https://answers.microsoft.com/en-us/msoffice/forum/all/project-online-sharepointcom-registered-app/4980afbd-4b50-4f11-88f5-314b28dbccc4?messageId=170f225a-7cff-45f8-82d4-5c53be37237e