Theoretically Lemmy could open a pop-up or redirect to sign in through your instance.

It would be nice if you could sign-in/comment directly from the blog. But I’m guessing the Lemmy api doesn’t provide that without making the blog it’s own instance

I don’t run Lemmy nor am I a tankie, although the creators are Marxist-Leninists, I believe. My youtube channel is mainly anarchist stuff. If you’re offended by the Communist Manifesto, maybe you should give it a listen, you might find you were offended by the wrong things.