My previous system is a Rainbird ME3. Flume and Rainbird work together. I think the Rainbird controller lets Flume know when the irrigation system starts/stops. All measurements and leak detection is still all done via the Flume app. It just knows how to categorize (outdoor) the usage based on the Rainbird controller’s reporting. I would be happy with this sort of integration too.
Separately, my water meter was replaced in February 2025 with a Master Meter Allegro which has a digital display. Works perfectly with Flume. Calibration shows it to be accurate. Not sure what percentage of new household water meters would be ultrasonic, would think those would have have higher power requirements and are probably more expensive. Municipalities would go for the cheapest option.