Mint Mobile and Apple Watches

No. Many MVNOs don't offer advanced features, such as support for the Apple Watch. That's part of how they keep the cost down...

You either switch to a carrier that supports the Apple Watch, or go with a GPS only model that does not care about the iPhone’s carrier.

And if you want internet access while away from your iPhone, you would need a cellular model and switch your carrier to one that supports the Apple Watch.

The GPS only model will track your exercise and carry music and podcasts that you can listen to while away from your iPhone.

NOTE: I have a GPS only Apple Watch, and I have been very happy for 6 years.

Also, the watch is $100 less expensive, and no $10 per month additional fee. So I save $220 in just the first year, and $120 each following year. So far I’ve saved $820 by owning a GPS only model. That is twice the price of my replacement Series 10 GPS only model.

It’s not up to Apple to make their products “work with Mint”. It's totally up to Mint to provide support for watches like Apple’s. Mint does not provide support at this time.

JayHanig wrote:

... It's a lot of money to tie up if I'm limited to Bluetooth distances from my phone.

Where you have WiFi coverage, a GPS only Apple Watch can also use WiFi, which typically has a wider coverage when you are at home. But, that does not solve your leave the iPhone at home and just have your Apple Watch when out of the house.