Hi,
Project Online does have the capabilities of project management, demand management, portfolio management with status and dashboard reporting (through PowerBI).
You can start from Microsoft Project page: https://www.microsoft.com/en-us/microsoft-365/project/project-portfolio-management
For the other subject, meeting, contact list, attendees, I would say that it is a completly different topic versus project and portfolio management. It is related to collaboration and team work. Project is a sharepoint based application so it embeds collaboration
features. It is also integrated with OneNote and more recently with Teams. So you can have a full O365 integrated approach.
I think there are many concerns in your question and you should contact a Microsoft Project partner to have a first discussion which will make you understand this ecosystem.
Hope this helps,
Guillaume Rouyre, MBA, MVP, P-Seller