For the full CS61A course experience, you would want to do the assignments and even try the exams, which are fairly difficult (they are the grade differentiator, for the most part). I wrote up a post about how to audit 61A as an external learner:
http://blog.pamelafox.org/2022/07/how-to-audit-cs61a.html
(I taught it for a few semesters)