@MarkCarline They just have outdated information:

• Home Assistant supports it since version 2024.10, it was even explicitly announced (won't let me link it) that you could use smart plugs with Matter 1.3 energy monitoring in the energy dashboard and they tested the feature with another brand.
• SmartThings, also in early October, updated the stock Edge drivers that handle Matter smart plugs to account for the standard power measurement attribute of Matter 1.3. For anyone interested the source code is here and you can see it subscribes to the ActivePower attribute and exposes the value to the platform to use in the user interface or automations.

These two platforms expose the energy data to the user and if Tapo launched the firmware update it would work as expected in them.

Then there are platforms that internally support it but only for developers, like Google Home for instance. The platform is certified for Matter 1.3 and the Google Home API supports the active power attribute, but it is not exposed to the user and cannot be used in automations either until they create a user interface for that and add support in the automation engine.