When I used mavlink to get pixhawk and raspi model 4 to communicate, but when I switched the airplane mode to Guided, his radio option didn’t let my arm. I have used QGound Control to view the errors above and also show radio options not adjusted, is it possible to get my pixhawk arm without a radio? Or is there some other way for me to make my drone work without going through the remote control, but directly using mavlink?
I think you can. By turning of the radio fail-safe maybe. It should work I think. I haven’t done it myself so maybe some other parameters to change but it’s possible.
Although, you would need a radio to tune and test-fly the drone until it’s tuned and can fly stably. Even than, I would strongly suggest you use a radio in case you need to make an emergency maneuver or something goes wrong.
how to “turning of radio fail-safe”？
I think you go to the setup tab in mission-planner and than in the hardware section. There should be a fail-safe page. There you can setup a battery fail-safe and turn the radio fail-safe off.
Try that and see if it works
There is a documentation page on the wiki that explains how to operate with only a GCS.