Thank you for your feedback. For now, you can use an API through Powershell to import .mpp files in Project for the web. You can learn more here: https://techcommunity.microsoft.com/t5/project-blog/import-project-desktop-files-to-project-for-the-web-api/ba-p/2031298
We are also looking into other ways to support import. Stay tuned for future updates.
An error occurred while saving the commentAnonymous commented
I'd like to vote for this functionality. As it is now it is useless to me