In order to activate it on Verizon you need a donor device that is supported on their network to use the IMEI to activate the SIM. Once activated you may not need the donor device any longer. It is common to use the discontinued Wear 24 smartwatch because it qualifies for a discounted wearable plan rather than a tablet or phone data plan.
Sadly the watch straps contain the GPS LTE Bluetooth and Wi-Fi antennas. They are easily replaceable, but the straps themselves may be hard to find. Check out the replacement guide here
Unfortunately the straps are also a weak point and after almost 2 years of almost daily wear the strap broke requiring sourcing a hard to find replacement.