You can create price alert here, copy coupons and view price history. What is best price?
Aliexpress
There’re some similar (or not) items on Aliexpress
Click here to search by yourself. Here are coupons that you can use.
Latest coupon code price check (UTC time):
Type: AMOLED (Corning Gorilla Glass), Charging Method: Magnetic (Warp flash charge), Multiple Watch Faces Support (APP supports AI wear / and automatically generates matching dials), Blood Oxygen Monitor Support, Memory 4GB, Brand OnePlus Watch (CN Verison), APP Name HeyTap, Battery Capacity: 402 mAh, Bluetooth Call Support, Pixel: 454×454, Compatible System Android 6.0 and Above / Not Support iOS, GPS positioning Support, Music Player Support (4G memory / can connect to TWS headset), Using time: About 24 hours, Multi-Sport Modes Support 110 Sports Modes, Operating Mode Full Touch, Size: 1.39 inch, Waterproof IP68 + 5ATM, Quick fitness test Support, Charging Time: About 2 hours, Standby Time: About 14 days, bluetooth Version BT 5.0
Banggood
Banggood warehouse is located in China.
Link: Banggood product page
1. ($129.99): BGf8af1e
2. ($219.90): BGc70579
coupon code has to be applied in shop’s cart after clicking “Proceed to checkout”. Click to copy code and open shop.
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k and https://couponsfromchina.com/short/5cd
Old coupons (from the oldest to the newest): band10, BGdc3b58, BGcdc638, BG5551ae, BGWRIBAND10, BG617f8d, BGad5ebd, BG2e1d87, 6GSGIT
(these codes were not working in latest coupon update, but you can check them out anyway)
Price history and price alert
Here is price history (for all/most countries) for OnePlus Watch 46mm Smart Watch CN.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood and Aliexpress (only if product name will be the same as on Banggood and I will post it on social media though, so it’s more like Banggood price alert)).