Hi，
Can you measure the voltage at this point? Please connect the battery and measure the voltage at this point in the picture to see how much V it is.

Have you tried SDWebServer? https://github.com/espressif/arduino-esp32/tree/master/libraries/WebServer/examples/SDWebServer

The signal value of 20 is very normal. In my case, it is about 19~23.

Please refer to here: https://github.com/Xinyuan-LilyGO/LilyGo-LoRa-Series/blob/master/examples/RadioLibExamples/SX1276/SX1276_Transmit_Interrupt/SX1276_Transmit_Interrupt.ino

@ak Around 800uA

This may not be possible on the existing basis, and part of the current consumption should come from the power consumption itself

I have an example using MicroPython before, but using ESP32, they are all driven by the built-in SPI module of MicroPython, you should modify the pins slightly and it should work fine

https://github.com/lewisxhe/mPython_ST7789

Please change the network mode to automatic to see if you can connect to the network correctly

modem.setNetworkMode(2);

Please refer to here MqttClient

Have you set SMS_TARGET correctly?
Set SMS_TARGET to the object you need to send, and your SIM card needs to support sending messages