We go through this with medical equipment ad nauseam
If it is permanently mounted in any way or draws power then the mount and the equipment have to be approved - the latter requires both bench checks for interference and fire risk plus a test flight. Approval is only for a particular model number and a particular aircraft type.
Other equipment does not need approval but the commander must specifically approve it and accepts full responsibility for security, fire risk and interference.
Insurance is an interesting point I have never seen tested. The insurance is not voided by carrying the equipment but it is interesting to postulate the situation were the equipment to cause a claim as the commander might be argued to have failed in his duty of care in giving permission where de facto it should have been refused.........