Believe it or not, I had a similar question just today.
However, what I want is to add tasks to todo.txt and somehow see them in my calendar (as events or as a task list, my calendar app supports task lists as well as calendars). I was thinking of a way to turn my tasks from todo.txt to calendar events or something and I guess a script on a server (I have a server and use it to sync stuff like notes and files) could watch for changes, parse them and add servers to Google calendar.
Anyway, it’s a slightly different question, and I can’t answer your question.
Maybe there’s a python library to work with Google keep notes, and you too could sync your todo.txt with your server (using syncthing) and watch file for changes, parse them and send them to Google keep using some API. I’m not sure if it’s possible but you could try searching in that direction.