I took the initiative of editing all of the Performance accessories that are currently in the database and changed their release type to "unofficial" given those products weren't sponsored, endorsed or approved by the companies they made accessories for.
As stated on the back of many of their products: "This product is not sponsored, endorsed or approved by [NAME OF GAME COMPANY]."
I'm certain there are many other instances of this in the database, but I decided to start with Performance first.
I didn't edit this particular entry because I'm quite unsure of it. I know there is a Performance Battery Pak for the Game Boy, though...
Of note, I also changed the publisher on many of the entries to "InterAct Accessories [Inc.]", which are the ones who developed/published all of the Performance products. And just to note, Performance is the name of the product line, not an actual company/developer/publisher.
Lastly, as soon as I can I will clean up these entries with more info and images.