I've been reading "Build" by Tony Fadell. It's just painful to read what Nest could have been. The V3 is nice, but there are still rough edges, the app loads slowly for example (no doubt because it needs data from the device via a cloud). And it is absolutely ridiculous how much trouble it is to let it talk to Home Assistant. Of course Tony is focused on the normal users (who just want stuff to work together, they don't care about open local APIs or Matter for example), which is a shame but understandable.
At this point: Please Google just opensource the firmware or something, add a local api and be done with it. It feels like they just don't want to support the device. Such a shame, it's such a nice thermostat (hardware-wise an ethernet cable to the heatlink would have been nice, to optionally drop the dependency on wireless, I'd pay for that).