HTMX is lower level. I think it would make a good web standard for libraries like Unpoly to build upon. Unpoly works best as progressive enhancement for frameworks like Rails or Django where most of the view logic is executed on the server. I love it, it's excellent. Just like Django (or rails), it's a practical tool refined after actual needs and experience, not a solution looking for a problem. And like Django it stood the test of time and is very well maintained.