To what extent is it permissible to eat meat that is stunned before slaughter in Germany, and is it permissible to eat meat from Muslim households without inquiring about its source, and how can one avoid the transfer of impurity (najāsa) in the home when eating?

Slaughter is not forbidden if the stunning of the animal—other than chickens—before slaughter does not lead to its death. Halal meat companies must observe this and dispose of any animal that died from stunning. There is no harm in consuming what they slaughter, and the principle of good faith should prevail. If it is proven that the parents eat forbidden meat, then it is obligatory to advise them by explaining its impermissibility. What dies from stunning is carrion and an animal killed by a blow. Carrion is impure, but impurity does not transfer except with wetness or moisture. The default state of things is purity unless their impurity is certain. One must beware of obsessive doubts.