Great news! I'm not using the full feature set (e.g. hyperscript) but really like the general approach as opposed to usual suspects like react or svelte. One of my last projects runs just fine on htmx + 3-4 stimulusjs controllers for all interactivity
hyperscript is a separate project. It is not a feature of htmx. htmx handles the hypermedia interactions with the back-end server. For pure in-page interactivity (hiding/showing side-navs, etc), you get to decide how you want to do it: VanillaJS, AlpineJS (my favourite), hyperscript, Web Components (lit.dev, etc), StimulusJS (what you used), a big framework component (Svelte, Vue, React, ...), etc, etc. htmx does not bundle anything into itself to make that decision for you. You may have thought hyperscript is a feature of htmx because sometimes you'll see the two used in examples (both have the same creator).