@Snort 

HomeKit compatibly is different than Shortcut compatibility.  The Siri compatibility is specifically with Siri shortcuts, although HomeKit is uses Siri the shortcut feature is different. 

Siri Shortcuts are essentially quick actions across your apps on iOS. They can perform an action automatically within an app in the background, or they allow you to dive into an app to get something done with a simple trigger phrase.  In other words these shorts are still be ran in the native app.  You are just using Siri and your voice to control the action, instead of logging into the app and tapping the button manually.  

HomeKit is a cloud to cloud interaction like Alexa and Google Assistant.  This interaction you use the 3rd party voice service to send a command to the Kasa account to activate said device.  This communication goes from one account to the other.  Until just recently we did not have a product compatible with HomeKit.  That product is the KP125 and is now available for sale. 

@Carl I do not understand much of what your wrote.

@Carl 

What part don't you understand?

@Carl 

That my non HomeKit Kasa plugs work fine with Apple Shortcuts.

But at the same time (except for the Kasa plugs sold at Target and Best Buy,) Kasa plugs are not HomeKit compatible for automation.

@Snort 

Apple shortcuts are not the same thing as HomeKit annomation.  Shortcuts allow you to run actions for apps that are running in the background.  Homekit links Apple's Home app to control compatible devices through a cloud to cloud communication.  This is how Amazon's Alexa and Google Assistant work with the devices they are compatible with.  

This is the reason why the KP125 works with Homekit and our other Kasa devices work only with Apple/Siri shortcuts.   

@Carl But why does it give Automation option on Shortcuts? (bottom of image)
I am still not getting why I can tap here with my finger and trigger with my voice here but not do any automation.

@Snort 

Its Apple's app, I couldn't tell you.  Perhaps automation is tied to the Home app which would be HomeKit.  I'd recommend reaching out to Apple support for that.  All I can tell you is what I have already explained Shortcuts are not HomeKit, and right now we only have one product that is HomeKit compatible, that being the KP125.  

@Snort There is an iOS app called Watt for Smart Devices that seems to do what I am talking about.
https://apps.apple.com/us/app/watt-for-smart-devices/id1465004830