I didn't find anything similar with search, so let me share my findings about these locks.
Firstly, they are better than you may think of them. For example, they cannot be open with shims because the shacke is locked at the very bottom, so you cannot reach locking element with shim. Despite they are cheap (about $3 or slightly more), they feel quite sturdy, and much better than locks with keys for the same price.
Secondly, they are relatively hard to open without password. As you all probably know, combination locks with few weels are usually quite easy to unlock - just make some tension on shackle, turn weels, and you will feel or hear when to stop. Combination lock with a dial are quite easy to unlock too - there are many tutorials. This lock is not as easy to open (at least I didn't find obvious vulnerabilities).
However, there is one thing you can exploit to try opening it without password.
Take into account that it is not resettable, so each button is pre-set to be part of the password or not.
Therefore, (I believe that) "opening buttons" and the rest of buttons are made on different lines on the factory to reduce cost of the lock. As a result, "opening buttons" and other buttons are slightly not the same - you can find some difference if you look carefully. They can be very slightly different color, different type of surface (more opaque or glossy), have different kind of scratches. You just jave to look carefully, and not only at frontal surface of buttons.
To prove it I told the principle to my wife, and she correctly guessed 4 of 5 digits off the password.
Good luck!
