Being so against using any sort of transpilation you avoid even TypeScript and JSX? Even though Parcel gives you these things completely for free, out of the box?
I do not think this approach would scale to a team in any good way.
Also with regards to using something like unpkg URLs in built code, whilst I a not completely against using urls for dependencies (ala deno), isn't there the huge risk that without pulling dependencies in at build time, those URLs will break or become overloaded or compromised?