You're not building a business, you're scamming people. You're just selling the same kind of bad products we can already find on Aliexpress. Those cheap knockoff look attractive on paper but, they don't even show accurate datas. Yes, they aren't as expensive as a Garmin but, 50$ for something that doesn't work is a good way to waste your money! Buyers with less money to spare would be better served with a used real smartwatch instead of this crap.
Here are an alternatives with similar price and better support: https://www.amazon.com/Xiaomi-Mi-Band-4/dp/B07T4ZH692