This Docs add-on adds a sidebar to Google Docs that lets you add selected text from your document to a Todoist project of your choosing.
Added tasks from this session display at the bottom of the sidebar.
The first time you use it, you will be prompted to sign into Todoist.
Disclaimer: I'm not affiliated with Google or Doist. Google, Doist, Todoist, and Google Docs are trademarks of their respective holders. Their use does not imply any affiliation or endorsement by them.