It is available on T-Mobile and US Cellular LTE
It is part of the MVNO carrier found on US Cellular's LTE and T-Mobile, the 5G networks, and will operate on them.
It has the needed cellular connectivity
It does not support most Android smartwatches today. But this may change with the launch of the Pixel Watch.
Who is bringing it to town
Several references have been given to Rohan, which is the company bringing it to town. This indicates users can get it directly from the MVNO.
Any additional charges
Google Fi may charge you extra for getting this feature. According to some insiders, the Google Pixel Watch may come in three models.
Get insurance as well
You can get insurance as well on your Google Fi. There is no need to get the protection plan and the hardware.