However you would just be able to do what you can do with SvelteKit (Parts 3 and 4). Not too different from what you can do with HTMX.
You would need to deploy SvelteKit but could have SvelteKit call your backend API for all of the heavy lifting and its deployment requirements would be minimal.
Yes, a bigger chunk of the JavaScript ecosystem takes longer to learn, but you can also do more with it. If you make an apples to apples comparison I think they're effectively in the same ballpark, and JavaScript is better just by having more resources.