Is Servo production-ready enough to replace or embed alongside engines like WebKit or Blink?

It depends on your use case. I wouldn't use it for a JS-heavy site. But if you have simple static content, it's probably enough. It's worth testing it out as a standalone app before integrating it as a library.

It doesn't crash as often as it used to few years ago. JS heavy sites might not work, and layout issues too. And internet gatekeepers cloudflare turnstile doesn't work.