The Apple A12Z Bionic is an updated version of the A12X, adding an additional GPU core, and was unveiled on March 18, 2020 as part of the iPad Pro (4th generation)The DTK Mac did not use the same A12 as the iPads, it had a lot of custom components tacked on which could enable desktop features like virtual swap memory. No iPhones so far are capable of running a desktop OS.
At its 2020 Worldwide Developer's Conference, Apple introduced the Developer Transition Kit (2020), which uses the A12Z processor with 16 GB RAM in a Mac mini enclosure, hence being the first Macintosh computer to use the Apple silicon architecture.