V2G will most certainly require G99 licience, although V2G is still in its infancy, facing regularty hurdles. The AI response above is mainly centred around the North American market J1772 CCS1 (Type 1) 5 pin connector. Fords charge station Pro is based around the F150 lightning truck and Wallbox targeted with Kia (EV9) usrs with the Quasar 2, which costs in the region of $6500.
Chademo is the only charging protacol with bidirectional charging enabled as standard since its creation. On that subject, Wallbox do a Quasar bidirectional charger in europe, thats based on the Chademo protacol, costing around €7,000.
Sigenergy approach to bidirectional charger is based around a battery module and DC charging for the home, but its a tied in approach, so not suitable for those who already have battery storage.
Renault particularly the R5 has an interesting approach, which I can see evolving with other manufacturers. The cars onboard charger instead of AC-DC converter is now bidirectional and a V2L type plug is used which combined with what Renault calls the Mobilize Powerbox sits on the wall and acts as the centre splitter. Not sure its on UK R5’s, but vehicles with onboard bidirectional chargers open huge possibilities where third party systems can be used, but a bidirectional charger really isn’t much different to a Solax or any other hybrid inverter.