Fargate isn't a competitor to Cloud Run (I wish it was) because it doesn't scale to zero in between requests and scale back up again when new traffic arrives.
It does scale to zero CPU when your application isn’t serving requests. See the pricing model at https://aws.amazon.com/apprunner/pricing/ for more details. It does not scale to zero memory, however, because customers have told us that cold-start latency has been their biggest pain point with Lambda functions. App Runner containers can respond to requests in milliseconds as a result.
Most of the stuff my company is running is made up of data pipelines and machine learning pipelines. So we have a lot of infrequent jobs that don't really care about latency.
When I say "scale to zero" I mean like Cloud Run or AWS Lambda: I define it as the service automatically scaling to zero (and hence costing nothing to run) in between requests, but automatically starting up again when a new request comes in - so the request still gets served, it just suffers from a few seconds of cold-start time.
I'm pretty sure Fargate doesn't offer this. It sounds like you're talking about the ability to manually (or automatically through scripting) turn off your Fargate containers, then manually turn them back on again - but not in a way that an incoming request still gets served even though the container wasn't running when the request first arrived.
I haven't yet - my projects (all based around https://datasette.io/) need full Python support, and it looks like Cloudflare Workers still only with with JavaScript or stuff-that-compiles-to-JavaScript. I don't think I can get Datasette working via the Python-to-JavaScript route, it has too many C dependencies (like SQLite).