If someone want to use such an app, it’s preferable to show an FOSS alternative that does it better

I think it’d be better to instead discourage the use of such apps instead of trying to shift them toward a vibe-coded app that happens to be open-source. It is not somehow less harmful or more ideal if someone’s computer is borked with an open-source app instead of a closed-source app. The less harmful scenario is not to use them at all, and that’s an easy stance to advocate for.