This is the first time I hear of HTMX. Thanks for the heads up on it.
HTMX has been great because I've just added a single endpoint in Flask that HTMX pings and makes it feel and respond like a single page application. You can have a flask endpoint, use Jinja to create the HTML and plug it into your page with HTMX. really nice and simple.
Flask + HTMX is the new hot sauce.
Really anything + htmx. That's part of the beauty of it.