If you're talking about the move from hardware to software authentication, I believe the change was reflected in the availability of both commercial and non-commercial HAP. An MFi requirement still stands for commercial, I believe, which requires hardware/chip.
Quoting myself from a previous thread:
Making your own hardware involves Apple's Homekit Accessory Protocal.
HAP, intended to help an accessory communicate with Apple's HomeKit, has two faces - commercial and non-commercial.
- In the case of commercial use, a manufacturer would have their own implementation w/their own (MFi licensed) products.
- In the case of non-commercial, an individual would use that version HAP with their DIY accessory/hardware, not intended for commercial distribution.
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Note further hardware questions may be better put to theHomeKit (Accessories) forum.