Hi!
I tried to see if someone else has already said this but I couldn’t find anything so apologies if I’m repeating an idea.
I really want to create a realistic lume watchface that glows in the dark and brightens in day light. Having some kind of expression that can control the opacity of layers in relation to the light sensor would be awesome. The darker it gets the brighter the lume will glow 
Timed opacity is the closest I can get at the moment.
I don’t think Facer has the ability to use the light sensor. I know on my Samsung watches it has the light sensor brighten the face when exposed to bright light like outside. But I’m not sure if WearOS watches also do this.
I think Fossils and TicWatches have this feature but not certain, suppose it depends on the hardware itself. Just think it would be a neat idea if we could tap into this feature if most watches have the capability. Could see some cool designs.
Yes, the automatic screen brightness is supported on Tic Watch Pro. I haven’t seen any way to access this feature via facer. If you find a way, I’d like to check it out. Could be used in some interesting ways! ie. photography themes…
The best solution I have found is to set opacity on the lume between Sunset and sunrise. Sounds like you’ve already got something like that cooking though.