I want to use CM4 as companion computer to my drone's flight controller. Can I power board and use the GPIO outputs without any IO boards, just module itself? I don't want to carry non-necessary weight.
You would need to generate stable voltage to power up the silicone. So you would need extra voltage regulation circuit (5V). Some pins need voltage reference, so you would need produce those. Some pins have to be driven low or high. This will spiral out into design of a custom carrier board. Then your only method of accessing it is over WiFi or shell from UART. Short answer is yes, with extra custom board and tone of knowledge. Why not use Raspberry Pi 4B or Raspberry Pi 0 W 2? Moreover, Raspberry OS is not a real-time system, you might run into trouble controlling responsive control loops.