We also have an actual german word for that, in addition to the phrases conveying similar meanings:

Egal.

Meaning something is irrelevant, does not matter, can be disregarded. So, something i give zero fucks about would be something that ist mir (scheiß)egal. Add swear words to your liking for emphasis.

I wonder if that’s from/related to the French “égal,” meaning “equal,” thus “it’s all the same to me.” I see German has its own unrelated word for “equal,” but borrowing another language for cursing purposes is as common as merde, pardon my French.