The "Sun" type has "Strength", but the other types have "Power". What are the units for these lights? Lumens? Lux? Candelas? They all default to 100, so maybe it's a percentage... of something? Does Strength use a different unit from Power?
I see there are already other questions asking about how they work specifically in Cycles, but in my use case I am making a scene in Blender and I want to export it to a game engine. I would like to know what units Blender uses for its lights so that I can perform a conversion where necessary, and verify the conversion is correct.
I also see another question with an answer stating that it's in Watts, but they said that this is not the case from experimentation. I would like to know the true units, and how it is converted when exporting, and also I would like to know how to convert Blender's light units to lumens, lux, and/or candelas so that I can convert and verify.
EDIT: I am exporting to GLTF using Blender 2.83 beta. GLTF's light behavior is well documented: https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_lights_punctual#light-shared-properties