I saw you need an electronic engineer specializing in embedded systems and IoT. But embedded systems may look complicated, when your prototype uses interfaces like UART, I2C, and SPI and communication through WiFi.
I develop firmware for microcontrollers like STM32(ARM Cortex M), ESP32, ESP8266, and SoM(systems on modules) like Raspberry Pi in C/C++, Python, and MicroPython, which gives me the confidence I can help you. I am very interested in your project, and with the immediate availability to focus on it
P.S.
Shot me a message with timeslots you're available today and I can run you through it on a call together.