Sorry for the late reply. If it helps, I’m using the HomeKit-compatible Eve Smart Plug (there are UK/EU/US versions) for exactly that scenario. It is able to monitor power consumption, and that can be used with HomeKit (and Shortcuts) to identify when the power point is in use, as per the (simplistic) example below. It’s more expensive than similar products (including the Hue one) but I’m finding its additional features useful for certain applications (and it has Thread support).
There are even more options in the native Eve app, including a history of the power the appliance consumed and an estimate of the annual cost (based on the price per unit you enter), as per the screenshot below.