I’m a happy man, the total power consumption is at 12µA !
I discovered that the 5V tolerant pins used as DIO inputs consume a lot of current!
Disconnecting the unused DIO-2 and rewiring DIO-0/1 to 3.3V pins solved that.
Setting the SPI and other pins with the following code did the rest:
digitalWrite(PA5, LOW); // SCK
pinMode(PA5, OUTPUT);
digitalWrite(PA7, LOW); // MOSI
pinMode(PA7, OUTPUT);
pinMode(PA6, INPUT_ANALOG); // MISO
digitalWrite(lmic_pins.nss, LOW); // NSS
pinMode(lmic_pins.nss, OUTPUT);
// DIO Inputs
pinMode(PA3, INPUT_ANALOG);
pinMode(PB5, INPUT_ANALOG);
pinMode(lmic_pins.rst, INPUT_ANALOG);
// Serial
pinMode(PA9, INPUT_ANALOG);
pinMode(PA10, INPUT_ANALOG);