Using MCP1700-3302E LDO for Arduino/ ESP32 Solar projects
You can try voltage supervisor like the TPS3839K33DBZR. It has a threshold or 2.93V. so when the voltage drops to 2.93V it will set the MCU into reset and keep it there untill the voltage rises to 3.3V. You can find adjustable voltage supervisor as well, open collector or push- pull configuration.