I think this is actually a real thing, but from like 10 years ago.
edit, there was a DARPA project that created a robot that could consume biomass as fuel, its acronym is EATR. According to wikipedia, it could “only” consume certain types of vegetation. But in the initial proposal, the developers also proposed chicken fat. So honestly, this probably exists and there might be a version of it that can consume meat.
https://en.wikipedia.org/wiki/Energetically_Autonomous_Tactical_Robot
I don’t know why, but this reminds me of the Dead Hand enemy from ocarina of time.