It's a Huawei fitness tracker from Techmania:
https://www.techmania.ch/de/Product/Detail/26869479
The issue is that the Huawei health app doesn't install properly and the product can't be used on its own. I did a lot of research in technical forums, seems this is a common issue - I think it's related to the Huawei/Google issues, at an operating system level. Neither Google nor Huawei admit the issue. I also tried installing Huawei operating apps but I think Google blocks this.
Amongst the functions on Techmani's website it lists:
Benachrichtigung bei Nachrichten (iOS/Android)
Benachrichtigung bei Anrufen (iOS/Android)
And obviously my band does not have these features, as it simply doesn't work with Android. So, does not function as described.
In UK law this could be breach of contract or there are rights under various consumer laws (item must be as described, fit for purpose, no unfair terms and conditions allowed, etc).
Obviously this doesn't exist under Swiss law, just depends on the company's terms and conditions:
https://www.techmania.ch/de/Content/Page/techmania-agb
Re warranty, they say I must take this up with the manufacturer myself (despite the fact that I have no legal contract with them), nothing for Techmania.
Honestly this is not a big expensive item and didn't expect to get any money back. I was mainly interested about the principles, because I will surely buy more things in the future, they could be really expensive, and I would like to have some protection if they break after a few months. It seems like it is quite risky to buy things in Switzerland.