It only needs to be making the contact so amps don't really matter that much.
I sometimes use relays out of cars or trucks in the wrecking yard for low draw things like this, but they are even overkill for something like the sense wire.
The under hood fuse panels on newer cars and trucks are loaded with them, and most made in Canada instead of China.
To buy one, 5 or less amps duty is plenty, but it could be a 30amp and it won't matter.
