[tetraca]

Having built sites of similar levels of interactivity, we would have used some sort of server side framework with a template library (A custom PHP framework+Smarty, Spring Boot+Thymeleaf, Python+Django), without any front end frameworks at all. We would use jQuery a little, and later some Bootstrap. But these days vanilla JS would probably suffice for what we'd generally have used jQuery for. This is probably a bit old school at this point, I'm sure.

[t0astbread]

jQuery is a relatively small dependency and it's still more expressive than vanilla JS so I wouldn't hesitate to use it if it felt appropriate.

One could also reach for something like Preact if some components are too complicated for manual imperative updates. You can use it without a build step and only for some parts of your pages. For compatibility you can ship a server-rendered component that you then throw away if the client has JS enabled (although that would require you to implement it twice).