Lighthouse is a lab-metric system while Web Vitals is a "real-user-metric" system. Both approaches are valid, and have their pros and cons.

Generally, lab metrics are convenient because you can run them whenever you'd like including before deploying to prod. But they can never tell you the ground-truth of what is really happening out there that real-user-metrics provide.

E.g. the FID metrics only make sense when someone actually interacts with your site. Lighthouse cannot know when people would interact and thus cannot calculate the metric.