I do think this is an interesting concept. Would API integration endpoints that users could configure directly to poll your service with their home automation assistants get past the need to be notified? If they could poll at their own pace, the could alleviate the uncontrolled cost.
Furthermore, that group may also just pull weather data directly instead, so may not need something like this.
Originally, this started as a Home Assistant automation for myself. I realized it doesn't actually require any sensors, just a location, so I decided to build something anyone could use.
Originally I built this for myself only as a Home Assistant automation and had been using it for years.