Any developer can now tinker with HomeKit products and prototypes can be built on top of popular boards like the Raspberry Pi and Arduino. However, once ready for market, the device will still need to get MFi certification.
Notably, Apple also made another major change to this process. Manufacturers are no longer required to integrate an authentication chip; rather, authentication can now be done through software.
Any existing product or future product can do this software authorization. The devices just need a firmware update. Apple said it would still have all the same heavy-duty encryption running on it. (Of course, companies who have already gone through the process of integrating the authentication chip onto their device might be a little annoyed with this update.)
These two changes could make a big difference in helping manufacturers get new HomeKit devices to market quicker. Over the last year we've seen significant increase in the number of HomeKit products available; however, we'd love to see even more!