After some light testing, this seems to work really well. I've had issues with other Javascript kernels for Jupyter and I personally don't care for the UX of Observable, so this is exciting.
Out of curiosity: what is it about Observable that you don’t care for?
Nothing huge, just don't personally care for evaluated output above the cell. Kinda breaks all the conventions of the command line, Jupyter, etc. Not that I couldn't get used to it, but originally Observable output below the cell but then switched in some update and I never really went back. Such a minor little pet peeve, I know.