I'm not sure there are any such devices made by consumer unit or panel manufacturers, designed to be incorporated inside their units. In any event, since the unit is likey to be made of metal, not the ideal environment to put a weak wi-fi transmitter!
But there are several products to do what you want. They typically mount outside the CU/panel and use a current transformer clipped round the 'live' wire of the circuit you want to monitor, normally the L tail entering the CU/panel, but could be (subject to meeting regs) clipped round the L of one or more individual circuits you might want to monitor.
The wi-fi one's I know are really add-on's to a completed installation, rather than an integral part of it, but others may know differently
I would steer clear of some of the Chinese versions on well known websites!
Here's an example, which I think would do what you want.
Purchase Shelly EM from the only Shelly authorised reseller in the UK. Shop Wi-Fi smart home automation now!
shellystore.co.uk
It includes a driver for a contactor, to remotely control the circuit you are monitoring, but implementing that might cause a compliance problem unless parts are from the manufacturer of the CU or panel that you are using.
