Ooo nice, I didn’t know about this. Thanks for posting, looks interesting, and framework agnostic to boot :)
(Edit: well, potentially at least)
I did try to make something like this a couple years back to deal with multiple renderers and a choose-your own set of various SSR techniques [0], but didn’t get very far with it in the end. I should have based it on Hono really, to get web standard Request objects.