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)