◇ Could this help me?
Yes. The diagnostic is clever precisely because of a detail the video does not state: an assistant fetching a URL generally does not execute page scripts, so what it sees is a fair approximation of a crawler that will not run them either. The fix is real, with one nuance to keep: the major search crawler does execute script, just on a delay, so a fully client-rendered site is usually indexed eventually rather than never, while many AI and social crawlers do not run script at all, which is what makes server rendering worth doing now. This is a general practice.
Fetch my site the way a crawler that does not execute JavaScript would, and show me exactly what content comes back in the raw initial response for each important page. Tell me which pages return an empty shell, whether the title, description, headings, and body copy are present up front, and what rendering strategy this project currently uses. Then lay out the options for delivering content in the first response, whether that is server rendering, static generation, or pre-rendering, with the tradeoffs of each for this codebase.