Apple Watch 5 and SIM card

Mint Mobile is not listed in the below link of carriers that support the Apple Watch.

The Cellular Apple Watch shares the iPhone's phone number.  This requires the iPhone cellular carrier to support the Apple Watch.  The iPhone carrier charges a monthly fee for this service.  In the U.S. the fee is $10 per month added to your iPhone bill.

iPhone Cellular Carriers that support the Apple Watch, which models, the radio frequencies each model uses, and the country where they offer service:

https://www.apple.com/watch/cellular

You will need an iPhone 6s, SE (1 or 2), 7 or newer, running iOS 13 or newer.

StephenShutters wrote:

Exactly. Mint Mobile uses T-Mobile’s network, and T-Mobile’s network works with the Apple Watch.

That an Apple Watch works on Mint is not because Apple Watches work on TMobile but because Mint has decides to support them. They could just as easily chose not to.

Exactly. Mint Mobile uses T-Mobile’s network, and T-Mobile’s network works with the Apple Watch.

You can't insert any physical SIM into an Apple Watch. They use eSIMs and are connected to your iPhone. They share the same mobile number with your iPhone. It doesn't matter if Mint is an MVNO on TMobile's network if they don't support the Apple Watch.

According to Mint Mobile’s website, Apple Watches are, indeed, compatible with the company’s cellular plans.

I'm not sure that statement means they support the eSIM on the Apple Watch. An Apple watch can work with any carrier, only selected carriers work with the cellular portion of the watch. A Watch can work with the paired iPhone with any carrier the iPhone works with. Since the link from Apple is from 2020, I would direct the inquiry directly to Mint, and not to the internet. And, the original question was to insert a SIM, which cannot be one. Only Mint can say if they can activate the eSIM.

Unless Mint is explicitly listed as supporting the Apple Watch, it will not work with Mint.