After quite some research and helped by many on Twitter the conclusion is that this part is most likely cargo of MH17.
It does not match the nose landing gear retract actuator of a B777.
It is weird that both sides of the actuator are not connect to another part.
MH17 did have aircraft parts (only 2.0 kg) and helicopter parts on the cargo manifest.
The cockpit and a about 10 meters of the fuselage came down in one part. Most likely this part was loaded in the forward cargo compartment under the passenger floor.