Gotcha. In that case, we'd probably classify it as an enchanted item—it would be rarer and more special than just a hart/nuggalope/etc., especially given that it could presumably walk forever without breaks and ignore most injuries short of losing entire limbs. (But for the sake of de-video-gamed "realism" it would probably still need to have some drawbacks, like particular frailty of the limbs, clumsiness on rough terrain due to sensing its footing less physically, being particularly noisy, etc.)

Sorry for taking so long to reply to you here!