Most code reviews I've done at work take between 5 minutes to 10 minutes. To assume the worst possible case of 200 students, 20 deliverable per student, and a 10 minutes meeting per MR you'd be at ~28 days (~84 8hr-days). Get 1 TA and you now have 42 days of the semester dedicated to 1:1 time (35%) and the remainder of the semester dedicated to producing learning content. Learning content (lecture videos, etc) can be produced ahead of time and in this case you can replace this with more 1:1 tutoring time effectively allowing you to give each student ~10hr (10 min * 20 sessions * 1/.35) direct 1:1 time over the course.

From the students perspective all they need to do is:

1. Write a "project proposal" where they define a project, define goals, schedule a checkin with you to see if that project is large enough (1/20th the grade of the class)

2. Watch lecture videos and go through exercises on their own time.

3. Write code and bring it in to teacher. (18/20th of their grade)

4. Demo their finished project to professor (1/20th their grade)

This does work for later classes. I never had the ability to test this workflow out for earlier (100-level) classes as all of those classes I TA'd for followed the same model you're talking about.

The 200+ level classes that followed the model I'm talking about had ~10% to 30% pass rate which was in line (~2x) with the pass rate of similarly leveled courses from our college's Math and Physics department which was used as a sanity check.

edit: that's not to say you're incorrect that it would be difficult to do at scale, this is just the way I've seen it done at moderate scale (20 to 40 students).