Since I started contributing to KDE in 2019 I cannot remember anyone working on Dolphin for MacOS specifically. That being said, I have heard of some people using Dolphin on MacOS and the Dolphin source code has some mentions of MacOS to make it buildable there. There is a good chance that anyone who knows how to build software can take the Dolphin source code, build it for MacOS, and use it there without any further modifications.
If that works, we can automate it and offer an official download of Dolphin for MacOS. The infrastructure is already there because of other KDE software available for MacOS.