I think you will find that the names are somewhat irrelevant as it is likely that the broken arm, 1? (yaw arm?), is unavailable as a separate part and you end up having to buy an entire gimbal assembly, with or without the actual camera in the camera housing.
3) might be referred to as a "camera cable for xyz" or a "gimbal cable for xyz" and IS likely available on the likes of ebay and other auction sites either as working second hand parts or pattern new parts. I treat "OEM" labels with some skepticism! At a guess this cable is likely to to be included in a camera-less second hand gimbal assembly (too much trouble to remove) and might be included in a new one.
2) might be "cover, right? hand side, pitch/roll arm for xyz" and might be available on ebay etc. second hand or in "'bags' of gimbal parts for xyz".
Besides, camera aside, safely extracting the working components from the old gimbal to use with a new yaw arm may prove difficult or impossible.
DJI are unlikely to sell you parts and officially recognised repairers are unlikely to be allowed to sell parts, that's what I found when looking for bits for a
Mavic 2 Zoom. A guess for the reasoning behind this is that the drone should really be inspected as there may be crucial damage that would be difficult for the layman to spot.
In addition, if the gimbal assembly is swapped, you would need to research whether or not it needs to be paired to the drone and how far along that process the layman can get without access to DJI software etc.