Manuscript is a relatively new product. There are many other writing platforms out there like Overleaf, ShareLatex or Scrivener. We’ve got requests for integration for all of them.
At this point we focus on Google Docs and Word for official integrations. We don’t really have the resources to consider all products out there. That said, we hope we can provide programmatic access to Paperpile so that it is possible for external developers to develop such integration.
If anyone is interested to develop integration with other products, please let us know.