"It's a $20 Bluetooth headset on your wrist that also tells time."
"Custom Android OS" does not mean it runs Wear OS or phone apps. It's a proprietary, closed operating system with no app store and functionality limited to what is pre-installed.
This product is for someone curious about the smartwatch form factor who wants to spend the absolute minimum. It offers basic notifications and the novelty of wrist-based calls, serving as a low-risk trial before buying a more capable device.
Anyone needing accurate fitness data should look elsewhere, as the lack of GPS and low-grade sensors make it a poor training tool. Users who value a polished app experience or durability will find this device frustrating. Its only real feature is its disposable price.