Is the iPhone SE 1st gen compatible with Apple Watch Series 6?

The first generation iPhone SE will work as long as its updated to iOS 14. The First generation iPhone SE is supported for iOS 14.

The series 6 Apple watch requires an iPhone 6s or later. The first generation SE was released later than the 6s so is included in those models.

Randy is just confusing things.

details here: link-> Set up your Apple Watch - Apple Support

No such thing as a 5 SE. Its either an iPhone 5, and iPhone 5S or an iPhone SE.

You can use the series 6 Apple watch with a iPhone SE updated to iOS 14, but not an iPhone 5 or 5S since they cannot update to iOS 14.

No it will require a minimum of 6S (running IOS 14)

If you have the second generation SE and it goes to IOS 14 or above then yes it should work.