This pin is Flipper TX on LPUART [Low Power UART] (so connect to RX on device).

For I2C devices this is SDA (Serial Data) pin.

Generic GPIO uses PC1.

CHECK: "LPTIM1.OUT/ADC1.2"

Devices:
- BME280[I²C] (SDA)
- BH1750[I²C] (SDA)