About Germany, §32 StGB doesn't require proportionality, the test is "Erforderlichkeit" or "necessity". So if you only have a gun and get attacked by a knife, you don't have to "make things even".
Of course, if someone is simply stealing a Catalytic Converter you can't really shoot them, as it's a bit much... you can point a gun at them, and possibly even shoot the air, that's easier to argue as self-defence. If they threaten you back, the situation changes.
The problem is having a gun in the outside, in Germany, good luck with that... of course, if it's someone stealing something inside your house, it becomes a home invasion, which is a completely different thing than someone stealing your property on the street.
It's way more nuanced than Texas, which has a bit more clear cut law.
Of course, if someone is simply stealing a Catalytic Converter you can't really shoot them, as it's a bit much... you can point a gun at them, and possibly even shoot the air, that's easier to argue as self-defence. If they threaten you back, the situation changes.
The problem is having a gun in the outside, in Germany, good luck with that... of course, if it's someone stealing something inside your house, it becomes a home invasion, which is a completely different thing than someone stealing your property on the street.
It's way more nuanced than Texas, which has a bit more clear cut law.