It seems to be hard to find an explanation for the lease gravity nuclear weapons strategy for Germany. I presume that they require US launch codes (and the F35

It seems to be hard to find an explanation for the lease gravity nuclear weapons strategy for Germany. I presume that they require US launch codes (and the F35 has a kill switch?). So what is the use for Germany? The fear in Europe (confirmed by Westpoint graduate Mearsheimer long before the Ukraine war) is that if Russia strikes a single city in Europe, the US will get second thoughts and not retaliate. Germany then cannot retaliate either, so what is the point? This is the reason for France to have its own nuclear arsenal and fighters.