The problem is, it's hard to measure how good a PM is, even harder than for engineers. The instinct is to use product KPI's to do so, but especially at BigTech company, distribution advantages and traction of previous products will be the dominant factor here, and the best way of raising many product KPI's are actually user-hostile. Someone who has been a successful FAANG engineer who goes to a startup might lean towards over-engineering, but at least they should be sharp on the fundamentals. Someone who has been a successful FAANG PM might actually have no idea how to get PMF.
> Here's what to do instead: Find your most socially competent engineer, and have them talk to users a couple times a month
This is actually a great idea, but what will happen is this socially competent engineer will soon have a new full-time job gathering those insights, coalescing them into actionable product changes, persuading the rest of the org to adopt those changes, and making sure the original user insights make it into the product. Voila: you've re-invented product management.
But I actually think it's good to source PM's from people who've been engineers for a few years. PM's used to come from a technical background; Google famously gave entry-level coding tests to PM's well into the '10s. I dunno when it became more fashionable to hire MBA's and consultants into this role, but it may have been a mistake.