plv8 doesn't have network access, but this can be done with PostgREST.

That said, we actually restricted the HTML content-type on our platform so that users cannot do this. This is because we don't want to get too deep into the "frontend" world, with ever-changing frameworks.

We've found that if we offer a small feature, our users demand feature-completeness. In this case we're better-off waiting until we have solve a few of the major database tasks (branching + migrations, scale-to-zero, edge caching, etc)

FWIW, I think it's very cool serving HTML through PostgREST. I would be pretty happy to do this personally