"Better interactivity" is subjective. You could argue that faster is better. Expanding and collapsing sections can be achieved faster and with zero JavaScript (which also makes it work on browsers with disabled JS) with a hidden input[type="checkbox"]. Aa for the media viewer, it could be a great exercise to try and make it in a similar manner with input[type="checkbox"] for opening/closing media viewer and input[type="radio"] for switching to prev/next image. This one probably requires browsers to support the `:has` CSS selector.

Also, if you want to further speed up your site, just like you said, the fastest way to speed up the site is to delete JavaScript, get rid of jQuery.