Well, there are UI changes and then there are UI changes.

https://htmx.org/essays/hypermedia-friendly-scripting

In general, I'd recommend perusing the essays to get a flavor of the style of web application we are advocating for:

https://htmx.org/essays/

And, if you want more, taking a look at our book:

https://hypermedia.systems

Why don't you stop posting questions to this page and take the time to read the Htmx landing page? It answers all of your questions. https://htmx.org/

Not required, you could still use js if you wanted.

Yep and that’s ok in some cases.