Looking for a word that means helpful but not needed

This may be an odd word (not even sure if one exists), but I will give some context and maybe someone will be able to point me in the right direction.

I am writing an essay on technology that is implanted into a human but is not vital to their lives. As I am writing, ‘extraneous’, ‘augmentation’, ‘non-vital’, and ‘cosmetic’ have been some words that I have used, but I don’t feel like any really capture what I am looking for. I guess augmentation is the closest for this, as it means to add, but it doesn’t really capture the idea of adding something that will be helpful but isn’t necessary. I can provide more context if needed, but I’m hoping that someone knows a word that will just hit the nail on the head.

An example of one of these technologies is the new tech coming out where you can implant a digital key into your hand so that when you open the door to your house it will automatically unlock. While this may be cool and helpful in some ways, it is obviously not necessary and the surgery to get this technology would be – just for fun (? I am struggling on this word!). Any help is appreciated!