You're both wrong, but you're only slightly wrong. It's been announced that those metrics will contribute to ranking in the bear future. Search for Core Web Vitals.
You are, of course, technically correct, which is the best type of correct.
There's been some level of performance weighting for a while (but only very slight and mobile-only), but I don't actually know what metric they were using for that (this was from ~2018, before any of those metrics landed in Blink).
AFAIK they don't? They use some of the metrics which are provided in Lighthouse (Largest Contentful Paint, First Input Delay, Cumulative Layout Shift) all play a role in ranking, but the score itself is meaningless.