The problem is known and definitely real. Scams are a persistent issue so this is definitely solving a real problem. Have a demo that works is also a plus.
It's hard for me to judge how effective this would be because you're essentially trying to solve several difficult problems at the same time: Message coordination across multiple apps, UX to nudge consumers to be less susceptible to scams and scam detection across modalities at scale. Scams also rely on a very low success rate with high payoff, so it'll be hard to find datapoints and iterate. Also keep in mind that you'd be competing not just with new anti-AI scam detection solutions, you're competing with existing in-house solutions to catch scams deployed at big tech platforms, as well as experienced cybersecurity professionals.
For the purpose of a product/demo (although again, good that you have a demo), I recommend solving one very specific problem that would've otherwise been intractable without your approach, and then either solving it and iterating to more general solutions, or pivoting to something else if it proves too intractable. Solving too many things at once is difficult.
I won't really comment on technical feasibility because currently most of the problems you're trying to solve do seem to be UX problems, and the stack seems relatively straightforward, if requiring high robustness.