> The "header frontend / body backend" split is a choice, not a requirement. I wouldn't make that choice.

I mention it because that's the first example on the official website, so I'd assume this is the right way.

Htmx is not a framework. It doesn't dictate a 'right way' to do anything. If you are interested in idioms that work well in practice, refer to the book that the htmx people wrote: https://hypermedia.systems/