Astro would call that an island: https://docs.astro.build/en/concepts/islands/

I guess this is our answer to the question of why Cloudflare acquired it in the first place.

I bet 99.9% of live Wordpress sites no longer have comments enabled.

So many WordPress sites don't have comments.

They can - it’s just more complex.

You just put the comments into something like firebase/supabase etc or use one of many off the shelf solutions. Free tier is fine.