I'm the creator of https://htmgo.dev and I'll say that is definitely the biggest issue I've run into with htmx. It's definitely not an overall replacement, you will have to either rebuilt the date picker from scratch in js, or find a vanilla js library

so unfortunately the major downside I see so far is it's fairly hard to find good open source vanilla js libraries for things, as most things seem to be written for react.

other examples include: - virtualized list - combobox