What are the pros and cons to buying a smart watch from temu?

Pro: it'll probably work well enough to get your notifications and maybe even your heart rate and stuff.

Con: it probably won't arrive. If it does, it probably won't look like in the pictures if it does, it probably won't work like described. If it does, it probably has done kind of cheep, toxic chemicals it'll leave in your arm. If it doesn't, it'll probably come with an app that drains your battery. If it doesn't, it probably sells your live location and notifications to data brokers. If it doesn't, it'll probably never receive software updates. If it does, it'll probably be broken by the end of the year.

There are actually a few relatively cheap smart watches that some people like to reprogram with open source firmware. You can get a Colmi P8 or a Kenboro K9 for less than $30 and flash WaspOS onto it. You have to get lucky and buy the right hardware revision but flashing new firmware onto those things can be as simple as downloading an app and loading a file into it. These devices are underpowered and software availability is limited, but at least with the open source stuff you can rest easy about your data not being sold.