For example, I have a small cron script that emails me today's showtimes for my local film museum (which shows old films on a large screen) along with the predicted score from Criticker.
It would be cool if there was some very easy way (I'm lazy!) of letting a non-techie benefit from this, without me having to deal with a publicly available server, storing their Criticker credentials, etc.
I guess the easiest way would be a Chrome extension, but I'm not a fan of the whole app store part, plus I don't want to have to rewrite in JS. And that still leaves mobile users in the cold, which is dumb.
Barring that, Github Pages is pretty good. You can get pretty far with a webapp that has some degree of caching/cookie/offline storage. Probably enough to display your local showtimes and maybe even interface with the user's Criticker – presuming Criticker has a CORS-enabled API. Automatic cross-platform UI and mobile support, no app stores or extensions. With Github Actions, I think you could even webpack a React app if you wanted.
But running it on a schedule and sending an email.... suddenly much more work.
I guess this might have been very useful as a Huginn module. Maybe Urbit matures to be a functional version of this. The problem is that today’s computing culture grooms people to be dependent on others’ servers/services, rather than being in control of one machine of theirs.
I wish something similar had become more common. I understand why all the platforms are focused on push notifications rather than pull notifications, but it's so much easier to write a bit of HTML/XML templating than to write anything with a PWA ServiceWorker and the Push Notifications API.
 The one app I built during that brief time was to poll NaNoWriMo for count API updates. It's a really simple app and was easy to customize with just an old school HTML method="GET" form. https://github.com/WorldMaker/NaNoWriMoAtGlance/