If you are a user of Microsoft Project Server on-premises version you can download and test the Microsoft Project Server 2019 preview, Download Here.
This new version includes enhancements to performance, scalability, reporting, accessibility and an expanded set of resource engagement APIs and also the robust collaboration and capabilities from SharePoint Server 2019.
Microsoft has the Project User Voice where you are welcome to provide feedback.
If you want to know more about the features for this version, check here: What’s new for IT pros in Project Server 2019 Public Preview.
You can check how to upgrade to Project Server 2019 here: Upgrading to Project Server 2019 Public Preview
If you want to see the difference between SharePoint Server 2016 and Sharepoint Server 2019 Preview, Microsoft has published a useful comparison, check here: Differences between SharePoint Server 2016 and 2019 Public Preview.