"Computing without Computers" - not sure how current the content is but some of it is very fundamental, offline.
https://teachinglondoncomputing.org/resources/inspiring-unplugged-classroom-activities/the-intelligent-piece-of-paper-activity/
We also had our UG students develop and write some teaching material as part of their courses. (useful for getting them to really think about the fundamentals and their own learning) https://www.codingcurriculum.com
