Like most users I do not have any smart solar panels nor grid usage devices in my home, so the new Energy usage feature in HA is completely useless for me. However I do have lots of smart lightbulbs and switch which I do know the energy usage of. HA has a n option to add individual devices, but does not let you manually specify their power usage.
It would be nice to be able to manually set energy usage in watts of each device. For example I know that my lightbulbs consume 12 watts each, HA already tracks when they are switchen on, why not also calculate how much power they used, it would also adjust it based on their brightness.