Curious how this compares to Melange which is used by Ocaml shops as well to double up on Ocaml for both front and backend (ahrefs being the major user and sponsor). Does this mean giving up a lot of the JS ecosystem (React, graphql, etc)?

My understanding is that js_of_ocaml has been around longer and likely has a stronger ecosystem, but Melange was designed more specifically to play nice with the JS ecosystem.