The problem is bioaccumulation: taking in substances faster than you can metabolize and excrete them. Eating something that has already accumulated something is worse than accumulating it from the same original sources. That's why you can do suicide by vitamin A poisoning by eating carnivore livers.
Prion diseases. Accumulation of different substances, like mercury, lead, strontium-90, and, a new contender to the list: micro plastics. And you'll want to have a look at a person's medication and likely want to make sure they've been off of it for a few days before consuming their flesh.
Of course health care in Germany is magnitudes better than in the USA. But there are some weird exceptions to coverage. For example everything around teeth and some things regarding eye sight and allergies. Apparently not having my eyes and nose swollen shut all the time is a life style choice which costs me ~50 bucks a month. At least they think I should be able to breathe which only costs me ~5 bucks every 4 months (north of 300 without coverage).
No.