Darling is the long-standing (albeit in a few years idle) effort to let macOS binary programs run on Linux similar to wine but focused on an Apple macOS layer instead of Windows. This summer, it has come together and seen some new developer contributions.
The Darling project just published the highlights of the second quarter of having new contributors aboard and making progress at various levels. They have begun stamping out several frames including AGL, Carbon, AddressBook, CoreServices and ApplicationServices.
Darlings AppKit implementation has also seen a number of improvements as well as working with nested frames. There was also a solution in 32-bit application support, and various other low-level errors. In fact, they continue to plan to support 32-bit Mac apps on Linux under Darling as a "selling point" for those who still want to run 32-bit Mac software with Apple as officially moving macOS to a 64-bit only world.
More details about Darlings development via the Q2 summary.