I'm asking this because the documentation is totally contradicting to itself on multiple occasions: Extensions overview page (https://developer.apple.com/app-extensions/) claims it's not supported. At the same time, on FileProviderUI docs page (https://developer.apple.com/documentation/fileproviderui) macOS is listed among another platforms and docs kinda generally suggest it is supported. At the same time, "add new target" dialog in xcode is missing "File Provider UI Extension" template under macOS. At the same time, it's can be easily be done by creating an iOS extension, then swapping SDK to macOS and UIKit APIs to their AppKit counterparts. This way, FileProviderUI actions DO appear in Finder. Problem is, after clicking the action, UI never appears and here's what i see in Console: default pkd Waiting on thread <private> until Launch Services database seeding is complete. default Finder [d <private>] <PKHost:0x600000c38cc0> Beginning discovery for flags: 1024, point: (null) default Finder [d <private>] <PKHost:0x600000c38cc0> Completed discovery. Final # of matches: 0 error Finder nil extension for provider ID (<private>), error: (null) error Finder Action with identifier (<private>) did finish with error (Error Domain=FPUIActionViewControllerErrorDomain Code=1000). error Finder FP Custom action sheet finished with error Error Domain=FPUIActionViewControllerErrorDomain Code=1000 "(null)" default pkd [d <private>] Final plugin count: 0 This is totally confusing, please elaborate.