HomeKit works with non-Apple connected devices like lights, switches, cameras, locks, etc. Apple doesn't actually make any such devices themselves. But as far as I know, you need an iOS or tvOS device to actually run the HomeKit framework and connect the devices together.
I applaud Apple for trying to make security for IoT devices less shitty. That said, Apple has never been able to make cloud services work well, and when they work at all they don't work on non-Apple platforms and they tend to get worse over time. So yeah, Apple's not an option for my home control needs either.
Or you implement a HomeKit bridge in software and use that to make non-HomeKit devices available in HomeKit, e.g. using
https://github.com/nfarina/homebridge
I don't believe you need a custom chip, but HomeKit does require some advanced crypto that many low-end embedded devices probably can't support. See the dependency list for this open source Go implementation of the HomeKit Accessory Protocol: https://github.com/brutella/hc#dependencies
Edit: Missed this line in the original article:
The issue, according to Lombard, is that Apple HomeKit certification requires a co-processor to handle device authentication. That co-processor is where the device’s encryption key is stored and handles the computing associated with encryption.
Looks like (for security purposes) Apple wants a dedicated crypto co-processor. Probably a tamper-proof chip that stores a private key, similar in concept to Apple's Secure Enclave.
