> You can use isolated JS scripts, or other approaches like progressively-enhanced web components
How would one use "progressively enchanced" web components? Maybe I misunderstand the intention behind this statement, but web components are either supported or not. There doesn't seem to be some kind of progression.
Given custom elements are pretty widely supported by browsers now, I assume you are referring to js being turned off.
In terms of designing for that situation - you can follow a pattern where your custom element wraps ( <custom-ele><stdelement></></> ) the element you want to enhance. If js is turned off, then the custom element defaults to rendering it's contents....
https://simonwillison.net/2022/Apr/21/web-components-as-prog...