The Tx and Rx pins 1 and 0 pins on the nano 33 ble are a hardware uart port accessed as Serial1 and independent of the usb serial. Look at a pinout diagram for the Nano 33 BLE as the pin closest to the edge of the board is 1( Tx ) and the next pin in is 0 (Rx). It's not what you would expect.
Pin 16, 17 are in Rx and Tx of Serial2 ESP32.
Pin 1 will connect to Pin 16 and Pin 0 to pin 17. Connect the grounds. Make sure the baud rates are the same for Serial1 on the Nano and Serial 2 on the Esp.
Post your code and your wiring diagram if you have issues.