I wrote this on the plane from Melbourne to Kansas prior to the Developer Summit. It's loosely based on the fenix 5 Timezone widget, but built as a watchface. Along with UTC and Local time in the main field, the upper and bottom fields can be customised from over 30 global cities. Each timezone is DST adjusted until 2030. Has anti-aliased graphics too.
I mainly built this for myself so I could track the time back home, but thought I'd clean it up and release it for everyone.
Get it here;
https://apps.garmin.com/en-AU/apps/39950356-c2f1-4f5d-a6a9-e0913711718c#0
I'll see if I can take the DST code and build a barrel for you developer folks.