A Bloomberg report referencing trusted sources claims that Apple is getting ready to release an LTE-enabled Apple Watch towards the end of the year, or possibly early 2018. The addition of an LTE modem in the Watch would mean the device could operate completely independently, increasing its appeal.
https://www.notebookcheck.net/New-Apple-Watch-will-pack-an-LTE-modem-eschewing-the-need-for-an-iPhone.240184.0.html
Finally, and others will follow. Now some devices are not available with lte variant in all countries, gear S3 frontier lte as example.
For me, that would be the first smartwatch I'd consider. It looks nice enough and you don't need a phone.