With Atatus, your teams can identify and fix slow page loads, route changes, poor performance of static assets, JS errors, client side logging for every user including long load times, specific errors, asset performance, web vitals, DNS, SSL connection from a single pane of glass.

Since Google came out with the Core Web Vitals it kinda became more important at my company that we track website performance on a continous basis.

We build our internal tooling with Prometheus for this, but it kinda lacks capabilities on all edges. What are you using to ensure your website performance is alrighty?

This is not really a use-case for Prometheus, as you already suggested by the lacking capabilities. APM suites have tooling tailored for this, e.g. New Relic or Sentry (but using these for this purpose only is overkill, otherwise expensive and vendorlocked), or you could use purpose-built js libraries. Alternatively you could instrument your frontend app and leverage tracing to get a better understanding of changes in performance and bottlenecks, which is recommended regardless of web vitals but from reliability perspective.

https://www.debugbear.com/ can track those for you and alert when there are changes. It keeps the full (Google Lighthouse) breakdown in the history.

We are using sentry.io on a per page basis to help us stay on top of it.

If we were not boot strapped we would take the step to test pagespeed after each addition and before it goes to page speed, but not worth it for now.

Might https://www.vitalfrog.com be interesting for your case? Basically does that, checks page speed after every change