A rain sensor just tells you if it’s raining or not. A rain gauge will give you cumulative rainfall values. I know there are DIY projects to make HA-compatible gauges but I’d rather have something out of the box, at least in terms of hardware.
I found this on Amazon, and it appears to be be a clone of a more expensive station by Ambient Weather. It looks like it could be made to work with HA as it has a web interface, but I’m not sure if an app is required for setup. The rain gauge also doesn’t seem super accurate, which is frustrating as that’s the only thing I really care about.
I have a weather flow tempest. Expensive and my first one died after a few years but it works well and gives you cumulative rain readings through its native ha integration.
Does it require an internet connection or can it operate locally? Does it need an app/account?
There is both a local and online integration available. Some of the sensors like the weather forecast (which is the most accurate weather forecast I have ever had for my location) are only available from the cloud, others are available locally.