Yes, the UX is a bit clunky and hidden now because I’m still experimenting with it but you can comment on any url with Nostur. Right now you have to paste the URL in search to do it.

Hopefully other clients will adopt it too and you could also comment from the browser eventually with something like nostr:npub1alpha9l6f7kk08jxfdaxrpqqnd7vwcz6e6cvtattgexjhxr2vrcqk86dsn browser extension: nostr:note1vcr77y8m4gz4qzusczyq8nrvlew56dlpt0czax4g8d6reaw5fpuspzhtje