Would you be able to add OneDrive support to the iOS apps since I don't use Google or Dropbox.
Also I would like to be able to add other file types to projects like PDFs.
We'll consider adding OneDrive support in the future. You can vote for it here: https://todoist.com/Vote/show/8414/.
As for adding PDFs on projects, you can submit a request in the Votebox https://todoist.com/Vote/.
OneDrive support would be a great addition!