Ok, so I set
SYS_COMPANION to 57600 and was able to connect to Telem2 of my Pixhawk using the example:
as well as the integration tests (change
make && build/default/integration_tests/integration_tests_runner -- --gtest_filter="SitlTest.TelemetryAsync"
I then tried to set
SYS_COMPANION to 921600 and it did not work, neither with the SDK nor with QGC. Note that I had to disable the "Pixhawk" auto-connection in QGC, otherwise it would just connect via USB. I then manually added a serial connection at the port and baudrate in QGC and it did not work but show a strange error:
My best guess is that baudrate 921600 on a Pixhawk (currently) doesn't work. I suggest you try to use
SYS_COMPANION and try again.