Its possible to run the datastar TS/JS SDK in a service worker, if you want to do (isomorphic with the backend) templating from there or just returning pre-cached html fragments.
The parent comment wanted a way to "serve" requests on the client device, so I suggested a way to do that that is also compatible with normal d* usage...
How to get the data to the client and keep it in sync is an entirely other problem that they'd face with any framework/approach. Would be foolish for some applications and perfectly possible for others. Offline/local-first apps are getting considerable attention these days, for good reason.
I'm a big fan and cheerleader of everything you've done. Keep up the great work.