Pros: price

Cons: the watch doesn't work and now you have lead poisoning

Just buy a cheap Casio if that's your budget. It'll keep better time and is less likely to end up in a landfill

You don't need it. Save your $.

Simpler question, why would you buy a Smart Watch?

IIRC Temu makes its business from super cheaply priced items.

Super cheaply priced generally means either super cheap quality or some really iffy labor rights violations* in third-world countries (I know that term isn't the term to use nowadays since it's a cold war relic but I can't think of a better term—lemme know if you know of one), usually both.

*Up to and including slave labor. (Yay capitalism!)

It might or might not:

• arrive
• work
• be genuine
• be fit for purpose

Cheap but probably won't work I'm guessing?

If you really want a cheap smart watch there's a bunch of reliable ones worth looking into rather than getting something random on temu. I haven't tried the Pine Time but it looks good if you like fiddling with the tech.

If you can put up with Xiaomi they make a ton of different options. I used a Mi Band for a few years and it kinda did what I wanted it to do better than my current Wear OS watch does

Pros: cheap

Con: you support temu, and slave labour.

Cons: Ewaste and bad for the environment. Get something High quality used like on Facebook marketplace or a thrift store.

Seems like asking for disappointment

if you want a decent cheap option, the wyze watch seemed okay

You'll be probably be happier with a higher quality watch than with one that barely works. I would not recommend going for an option because it's cheap, instead go for the one that's good enough for you needs.

No need to buy the same one as I did, but I have been very happy with my "not the cheapest, not the most expensive"-garmin watch for years. It is reliable, does what i need it to do and is not so expensive that i am afraid of breaking it for instance. I did need to make choices to be able to get it, i could not spend that money on other things, but that only made me feel better when I got it.

More on topic: it's easy to find accesoires/replacement parts for my watch, it's easier to get it repaired, both at garmin as well as a local shop, the software has a lot of integration option with other software (strava, komoot, etc.) and i can download apps and watch faces other people with the same watch built and i can be sure my alarm goes off in the morning. I don't expect the temu watch to have these things. For me it was worth to pay a bit more. Sidenote: I did get a screen protector for my watch from AliExpress, so apparently I'm not against that 😏

I have some strict rules about buying things where I cannot verify the used materials:

Nothing that goes into my body
Nothing that goes on my body
Nothing that touches my food
Nothing my pets touch
Nothing that needs to be plugged in or charged

A smart watch violates multiple of those rules. I wouldn't want to risk it.

As someone who has bought a fair number of smartwatches and fitness trackers and always over-researches every decision I make:

• See the rest of the replies for info on cheap smart watches. They're basically a cereal box toy.
• Depending on what you need, the MiBand or Amazfit bands had excellent battery life and there used to be 3rd party apps for your phone that did a much better job collecting and displaying your stats than Zepp or MiFit (the official apps) did. I miss my 1.5 month battery life. Its also possible to use gadget bridge so it's all 100% offline though I understand its still a bit more rudimentary than a corporate cloud-based solution. I remember the bands I got from them running $25-50 USD
• Used Garmin devices or previous gen garmin devices can be had MUCH cheaper than list price on Amazon or so. I picked up a Fenix 6 a few years ago for less than half of the $600 list price. I love the lack of touchscreen because the button navigation is absurdly fast and no mistouches! This suits how I use a watch much better than trying to put a tiny a 2x2cm touchscreen on my wrist. These are fitness watches, but some have a few smart features. Depends on what you plan to use it for I guess.
• If you are a nerd (a good thing) and want to contribute to a cool project, Pine Computers, which makes the pinebook, pinetab, pinephone, etc. makes a device called the pinetime that is basically a smartwatch that is open to the community's hacks and modifications. I haven't bought one because my biking depends on my Garmin stats, but I am tempted to grab one to mess with it.

None of these are fancy "smarts first" watches like an Apple Watch or an Android Watch. I found I needed less smarts than I thought as I usually carry my phone at all times anyway. It is nice to have the doorbell ring on my wrist and to reply to texts by choosing from a few pre-written responses while biking, or otherwise unavailable to text. If you really want a bunch of apps and integration with your phones OS, Apple and Android are the big two and its not really feasible to go 3rd party for the same experience.

It's cheap

Pros: Might look cool, is cheap.

Cons: Won't be very durable, the app for it will be shitty and closed-source(probably malware), the battery will probably suck, any vital sensors won't be accurate, the screen will probably suck, and it will probably have a bad UI.

In summary: Save up for a better watch.

Pros:

• Cheap
• May still have regular capabilities
• not a big deal if it breaks
• They usually don't require "service," just Bluetooth and being connected to a phone.

Cons

• Usually they require an app, that could just be Spyware
• it will not last long
• the capabilities it will have will be a poor imitation of the original.
• Could be irritating (to the skin). It may not fit right.
• Poor battery life
• Additional E-waste when you do get rid of it once it dies.

Pro: Price, Convenience, Looks

Cons: Much like buying an "iPhone" from Temu, the price is usually reflected in the quality.

Don't get me wrong, there are cheep smart watches if you look for them or go second hand. But what you'll find advertised on Temu isn't it.

Build quality is usually the first to suffer, but you'll find mislabeled battery info a 500mah instead of the promised 1000mah. Or an LCD instead of an OLED.

But those are things we can adapt too. The biggest problem is software. That'll do and close enough has been the name of the game for years now. And sometimes "smart" just means it can (badly) track your steps and pretend to check your heart rate with a led pretending to be a sensor.

Alternative

If you are looking for any budget electronics try looking for last years or a few years ago models. I got a Garmin Forerunner 235 in 2022 for 1/5 of its asking price because I found a deal on eBay.

I'd also look into the landscape of the market you are buying into and seeing who is actually making these things, and what is running on it.

For smart watches I found the answer was

Apple

Android with Watch OS (Samsung google and many more)

Garmin

If the watch isn't running android watch os or is made by Apple or Garmin. Assume its good too be true and look into it more, or look elsewhere.

Good news China is lazy and one clone usually is made by many factories and someone else made a video about it. Might not be the same name, but it'll be close enough.

CMF watch, the old one, is a nice, cheap option, that works with Gadgetbridge, keeping your privacy intact.