Watched once again Betaflight for Beginners | The settings you need to get your drone in the air.

Some notes for future self.

GPS didn’t want to start working.

Set baud rate taken from GPS module datasheet: "Set baud rate taken from GPS module datasheet"

Set protocol from same datasheet: Set protocol from GPS module datasheet

It stays unclear how do I setup TX/RX channels for GPS and radio receiver if at all. I set GPS receiver and radio receiver on lines which match RX/TX channels where they are soldered. But that UART channels, not RX/TX channels.

GPS receiver is soldered to RX/TX

Here are final settings:

Final settings

Finally everything worked and I firstly got self built drone in the air:

Self built drone in the air