I'm more a backend than frontend developer (by which I mean I can use Livewire, but have never used React, Vue.js, Inertia etc. and my eyes glaze over when people start talking about them. Paradox of choice etc.)
Supposing you're builidng a web app which is primarily for user data input using some long/complex forms (but with a nice UX, obviously) for eventual uploading via a Laravel API.
You still need to be able to complete the form if the device is offline, e.g. by storing submissions in LocalStorage or IndexedDB for sending later. Ideally, there'd be some basic PWA stuff so you could go to the initial URL without a web connection too.
That's about it really. Not a complex website otherwise.
My tool of choice would be Vue.js to add the 'head' to your headless API. I would in the first instance keep it simple. There are loads of good tutorials on getting started with Vue (including on this site).
You will need a script to detect whether you are on or offline and a routine that either writes the data to the server or localStorage again there are helper classes to do this. You might consider a css framework such as Tailwind or UnoCSS.
@richardhulbert thanks - I did a bit more searching after posting and was leaning towards Vue.js too, so good to have it confirmed. And the (official) tutorial feels quite familiar. I use Tailwind already.