I’ve forked the GrumpyMeow’s addon and applied some fixes, but it still has some issues. Most notably, it seems to read battery state probably only shortly after the first connection, and then ignore it until HA restart. But it seems to work much better than the original addon: GitHub - v6ak/sonicare-ble-hacs: Sonicare BLE HACS integration
My main reason for the integration was smart charging that keeps around 50 % of charge. I’ve kind of succeeded – when I have no information about battery state, I blindly charge for some time (15 minutes, I think), otherwise, I decide based on the battery charge level. But still, the ESP32-based integration seems to be worth trying.