MAVLink v2 provides security with signing: https://ardupilot.org/planner/docs/common-MAVLink2-signing.html

That being said - I don't think that you should rely only on this feature alone. Security should be handled by technology used to transmit packets. For example commonly used WFB-NG requires you to setup keys on both drone and ground station to work at all. If other technology is used - that technology should use similar approach.