Of the items you listed, I looked at them and the ones I feel that you two should go for are as follows:
Collar and leash:
1. The first one looks decent, if you get a small lock, you might be able to lock it through one of the holes to prevent it from being taken off. It looks sturdy enough to be used with a leash just fine.
2. Second one you linked looks rather flimsy and I would avoid it. Looks okay for looks but for use of a leash, it doesn't appear to hold up with time.
3. This one looks cute and is more of a pet collar.
If I had to pick, I'd go for one of 1 and one of 3 and use them according for the role if you two are willing to share said collars. If not willing to share collars then base it off of if both of you will be on a leash or not.
Gags:
1. I definitely like this one more than the other and it's lockable to boot. Get two of these so you can both enjoy them together. Also they come in pink as well so can get both in black, one pink and one black, or both pink. (Personally, I vote pink for you two)
That other option you linked with the set, I'm kind of concern about how that entire set is so cheap for the number of pieces.
However, if you really want to make the one leashed or bound or whatever really feel helpless, try these:
https://www.amazon.com/ALMYMM-Petpla.../dp/B093SHZT4X