Just to follow up on email queries about course sequencing, there’s some more info in the docs about this, see: Publishing your Moodle Course to Oppia — OppiaMobile 0.12.19 documentation - although probably this needs expanding a little.
Some considerations here when using the sequencing…
If you’re just using this to try to force a pre-test to show, then it would most likely be best to put the pre-test into the ‘topic 0’ in Moodle (see: Adding quizzes — OppiaMobile 0.12.19 documentation). This way the user will be forced to complete the pre-test before they can access the rest of the course, but once the pre-test is completed, users will be able to jump around all the rest of the content freely. In this case you can also leave the course sequencing as ‘None’ on export from Moodle to Oppia.
If you select the “sequencing with a section”, users will need to complete the activities in each section in the course in order, however they will be able to jump between sections, so they could start multiple sections at the same time.
If you select the “sequencing within a course” then all sections/activities in the courses must be completed in order, so the users can;t jump ahead to different sections/activities before all the previous ones have been completed.