Most states we offer the course for can be completed fully online. The few states that have additional education requirements are NJ, NH, and AL. New Jersey and New Hampshire both have proctored exams, whereas Alabama has an in-person eye exam which must be completed in person.
Each state has its own landing page. Below is an example of the Arizona state course landing page (https://www.boat-ed.com/arizona/) , under "Get boater certified in 3 steps", you will be able to tell or not if the course is fully online.