They only work whilst you continue to wear them. A bunion is a laxity (so maybe they have been stretched) in the ligaments which have allowed the bone in your toe and the metatarsal to become misaligned so rather than forming a nice straight line they look like this < with the point being the bunion that you see on the outside. here is a link to an Xray picture of a bunion:
and a normal foot for comparison:
The only way to permanently correct it is surgery to either shave down the bones or tighten up the ligaments and pull everything back into place.
Bunion correctors force the bones into alignment and hold them there, but often very painful and as said before only work whilst being worn. They are also considered to be a medical device in the UK and therefore should be CE marked however most of these dodgy products are not.
I used to work in Footcare R&D and the amount of those that crossed our desks was phenomenal not one having any scientific backing. Your options are either to pad it so you don’t irritate it further or have surgery to fix it.