Update Alexa Skill state from external, non-voice sources, especially w.r.t. Echo Show
My smarthome product reacts to Alexa commands. But sometimes I want the device to tell Alexa about its state. Let's say my product has a volume slider... I want to tell Alexa when that slider is used and have my skill update the volume indicator on screen (echo show).
You can imagine this might also apply to stock tickers or weather updates or any outside information that might change between utterances.
If I recall correctly, this kind of thing is available in "smart home" skills, but that archetype was too restrictive for my purposes. My skill is just a normal "custom" skill and apparently this reverse flow of information into Alexa (vs out of alexa) isn't possible.