As a Mac user in the mech community, I've gotten used to typing on keyboards designed for Windows to operate Mac OS. 95% of the functionality works right out of the box, and the rest can easily be configured with Karabiner. That said, it is nice to see a mechanical keyboard designed for Mac OS, and I'm sure I'd enjoy using it.
The #1 issue I see is that precious space on the keyboard is given up for placing a phone, but modern-day iPhones and Android phones probably wouldn't fit in the space provided. The photos show an iPhone 5c, which is a lot smaller than the 6s and 6s Plus on the market today. At least iPhone SE users would still be able to use this keyboard as designed.
The phone size issue is a deal breaker for me, but in general I still think this is a cool idea. I use the VB87M to type on my phone all the time.