I had to install several dependencies through homebrew, ignore some default dependencies that don't make sense on mac (wayland, pipewire, etc), and then it worked.
The build command I used, for reference: kde-builder dolphin --ignore-projects wayland plasma-wayland-protocols wayland-protocols kglobalaccel kpipewire kwayland selenium-webdriver-at-spi baloo packagekit-qt baloo-widgets
Note also there's some mac weirdness with the Dock where some kioworker process might show up as a separate icon. I packaged it in dolphin.app MacOS bundle, gave kioworker a Info.plist with LSUIElement=true, and that got rid of the Dock glitch.
So, I wouldn't say it's entirely painless to install. But if you're sufficiently annoyed by Finder, building Dolphin can be worth the effort.