There are some wireless valves on the market already, such as Orbit’s wireless valve:
https://www.orbitonline.com/products/hose-watering/timers/hose-faucet-timers/1-dial-1-outlet-digital-timer/1-dial-1-outlet-iristm-hose-faucet-timer-with-brass-swivel
which requires an Iris controller hub. Technically due to the requirement of power efficiency, these wireless valves do not have built-in WiFi, but instead have Zigbee or Zwave inside. That’s why they require a hub in order to connect to the Internet.
I was thinking of developing something similar, but power efficiency is a challenge and the requirement of a hub is also a hassle. However, if you are OK with the valve being powered from an adapter (instead of a battery), that should be fairly easy to solve.