Hey Roger, and other people.
I just created one more AVD Template OnOff and Dim AVD with Default Flowcards (with Flow).
This to explain how Homey handles Devices classes and capabilities.
Device Class doesn’t create anything in Homey, as far as i know.
It only reacts.
Capabilities (what i call Fields) are what creates Homey default flowcards.
For instance, when a Device, no matter the class, has an OnOff capability (only one real OnOff can exists), you will get several flowcards: Devices Turned On, Device Turned Off, Turn On Device, Toggle Device on/off and Turn Off Device.
All the cards on the next image, are created because the AVD has a OnOff(button)+create-flowcards and a Dim(number)+create-flowcards.
This is why there is a Create FlowCards property when you select a default ShowAs type.
Back to Device class.
The example AVD can be turned On Off / dimmed through the flowcards in the image above.
But if you use Default Zone/Class flowcards, it would only react if you have the same Class.
Also other apps, like Group search for classes (sometimes).
Thats why i included the Class option.
Lets say you use the AVD as “real light control”, then you might want it to react to the default flowcard: Turn [[device-class]] On/Off.
If you put this on Turn All Lights On, the AVD is only gonna react if the class is Light (and it needs the OnOff button with flowcards).
I hope this clarifies things?