I think you need to consider how the bridles fit. I would want shorter cheek pieces and a longer crown piece.
Both the bridles you have on the original post put the square cornered buckle in a scary place beside the horse’s eye.
If you can’t do better fit wise, look for a bridle with rounded buckles.
The curb strap on a snaffle is called a bit hobble here. It is essential if there is no throat latch.
It stops the bit from being pulled thru the mouth. The hobble should be snug enough to keep the bridle on the horse’s head if the horse dislodges it (I saw a horse vigorously shaking it’s head because of flies can do this).
A one ear set up is for the show ring, and showing off a lovely cheek/throat latch.
Never use it for trail riding, or schooling a horse that is not completely obedient.
I agree with the posts that say a snaffle bit really should have a headstall with a brow band and throat latch