I'm not a gunsmith, nor do I have any direct word-of-mouth from any gunsmiths I know, regarding this issue, since I've never asked about it.
That said, I have read a few threads on the likes of the SOTAR private FB group regarding the various online certification programs, and from both students as well as recognized gunsmiths, the sentiments- and experiences-of almost always are negative.
Past students in-particular cite that too much of the coursework was simply YouTube videos, and that even the Associates Degree, for those who seek it, doesn't translate into favorable hiring in the industry (literally, one post said, verbatim, that "none of the manufacturers cared"). Text books were reported as being often only partially correct or outright incorrect and out-dated. Many recommend that even if the perspective student is thinking about using their G.I. Bill benefits, to save it and use it for something better - and to definitely not pay out-of-pocket or take out a loan for it.
Recommendations from the known smiths are to enroll, physically, in an actual Gunsmithing School (like Trinidad State Junior College), and then to find a Master Gunsmith to Apprentice under. In the meanwhile, if you don't have the knowhow already, attending a local tech school for machining, blueprint reading, manual mill/lathe and CNC would help you get a leg up, once you do enroll in such a program and start your apprenticeship.
Specialized courses -such as SOTAR's- also exist for in-depth dives into specific platforms. Having attended a one-day seminar from a local smith (
https://www.recoilweb.com/dave-laubert-defensive-creations-80917.html and
https://americanhandgunner.com/discover/exclusives/best-gunsmiths-in-the-u-s/; and he made the top - I'm extremely lucky to have someone of such renown here, locally) about the AR, the know-how I gathered in even such a rather informal context (the class was designed for end-users/hobbyists) was huge, and I can only imagine what a dedicated class like those offered by SOTAR or SOLGW, like the late William Larson's work, would offer in terms of knowledge transfer.
Best of luck on your quest!