1.Here are three methods to backup and restore project server: SQL Server tools, SharePoint Central Administration and Microsoft PowerShell.
Please refer below articles to backup and restore project server. (They are also work in the 2019.)
https://learn.microsoft.com/en-us/project/back-up-project-server-2013-by-using-built-in-tools
https://learn.microsoft.com/en-us/project/restore-project-server-2013-by-using-built-in-tools
2.Follow contents in this article to identify Project Server databases in a SharePoint farm.
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