Isomorphic rendering seems horribly inelegant.
My first instinct is to just use server-side rendering for this, although that may not be possible since posting a comment involves rendering part of the page on the client side.
In light of that, my second instinct is to render entirely on the client side, but then Lemmy won't work without JS, which may or may not be a problem. Mastodon seems to get away with it, but I dunno if Lemmy can. Also, client-side rendering makes it difficult to avoid breaking the back button, which the UI currently does.
Sheesh. Web development is such a mess.