According to Rigger 3, a walker-drone is capable fo performing a kick maneuver in combat, but it doesn't give rules for the damage codes, or just exactly how that works.

My intuition tells me the code would be something like (body-squared)Light Stun or something, since (body-squared) is the default strength for vehicles with mechanical arms, and because unarmed combat is usually light stun.

Then again, you're not being kicked by a soft humanoid with about the same mass as you, you're being kicked by a car (in some cases)... so maybe it should be physical damage. I'm not sure.

Also, would this count like the kick maneuver in Cannon Companion, with +1 reach, but with a penalty to any incoming attacks. I doubt it, but I wonder what other people have ruled when/if this has come up in their games.

Unarmed is usually moderate stun. Other than that, I see no obvious flaw with your math or reasons.

Haha, oops, yeah, my bad.

Treat it as an unarmed attack similar to a Critter attack, with 0 reach and (Body x 2) M Stun.