Things like that are why it's completely unreasonable to expect websites to work without first party Javascript. Utterly basic and mundane functionality is gated behind Javascript.

Building the mundane in the absence of JavaScript isn't some small thing you can build. It's going to require you to rebuild your entire site around the idea. Things like a searchable dropdown will now turn a single page form into a horrifying multi page mess where you get sent to a page for just the dropdown and the search box and selectable options, which then send you back to the original form. That is going to require you to store a lot of the form data on the server to keep track of what you entered across pages rather than let the browser do its thing.

The noscript crowd should have lobbied for a better HTML instead of rallying against JavaScript.