Could anyone recommend an ultra-low power consumption microcontroller and transceiver for wireless communication of a Piezoelectric sensor(preferably fit LTC3588 energy harvester)?
Take a look at our artemis boards https://www.sparkfun.com/search/results?term=artemis or the esp32 variants that we sell https://www.sparkfun.com/search/results?term=esp32
Both of those processors have ultra low power modes/config options…look at the examples online when you get started
Edit: apologies if you specifically need WiFi, only the ESP32s above have WiFi…both the artemis and ESP32 have BLE