Could any of the Honeywell/Resideo employees lurking here perhaps enlighten us as to the difference between the Honeywell 'Home' API and the TCC API, other than TCC's API being unofficial while Home is publicised?

https://developer.honeywell.com/api-methods

The Evohome TCC app on iOS starts up with a splash screen that brands it as Honeywell Home but then the Home API webpage does not mention Evohome as falling under 'Home' and indeed it doesn't. This is confusing. Also, there is a Home API category 'Smart Home Security' which seems not to encompass Evohome Security or Le Sucre. Is there any API for them?

Finally, how can one get an API-key for TCC these days? Emails to HoneywellAPISupport@honeywell.com are ignored. In the past, we were told on these forums that Honeywell wanted us all to have our own API keys...