Ok so I saw most of these updates whilst I was on holiday so have been eager to try.
Running 3.1.1_1437 on Pixel and findings are as follows:
Gear s3 Frontier using TL Casual Golden God face
Flight mode using dark blue screen 100-0% in under 6 hours (on a plane so no ability use the device to any degree) 16.7% usage per hour
Normal use light blue screen 100-33% in 14 hrs 4.4% per hour
Normal use yellow screen (default colour that comes with face) 100-75% 11 hours 2.3% per hour.
As you can see very erratic usage and only one face. Will try another tomorrow but still have to pack a charger if I'm going away for the weekend which isn't acceptable but can definitely see you guys are making progress. Keep up that focus on getting this nailed and you'll be on to a winner