That happens when you google idioms in other languages ... you have no clue about the actual usage. And they are usually not one-to-one.
German "das ist mir Wurst" is also a lot weaker than "zero fucks given", at least use something stronger like "das interessiert keinen Arsch" (no asshole cares). Also "zero fucks given" in the sense of "irresponsible, he just does it and doesn't care who gets hurt" doesn't really have an equivalent idiom. Maybe "als druff" (just go full power straight ahead) or something.
I've never heard "als druff" but I'd like to add "das ist mir Latte" as a variant as well as "das ist Jacke wie Hose" ("jacket like trousers", which is more like "potayto, potuhto") and as others have pointed out "das geht mir am Arsch vorbei".
But none of them is an exact match as there's no perfect overlap for all situations to which "zero fucks given" can be applied. Which isn't too surprising as most idioms and even most words don't map 1-to-1 between languages even when they share a common root.
Yeah, "das ist mir Wurst" doesn't seem strong enough. "Drauf geschissen"/"Scheiß drauf" ("shit on it") maybe? Kinda close to "not giving a shit" (or "fuck") and also kinda works for the irresponsible case, "Er scheißt drauf, ob er jemanden verletzt".
German "das ist mir Wurst" is also a lot weaker than "zero fucks given", at least use something stronger like "das interessiert keinen Arsch" (no asshole cares). Also "zero fucks given" in the sense of "irresponsible, he just does it and doesn't care who gets hurt" doesn't really have an equivalent idiom. Maybe "als druff" (just go full power straight ahead) or something.