Screen Saver Exporter, developed by Late for Dinner Studios, exports your movie to a screen saver in one click from After Effects and Premiere Pro. It supports both audio and video, and a single plugin covers Mac and Windows.
Exports go directly to a .scr file or an .msi installer. Version 1.32 added the ability to export a macOS screen saver from Windows, and those exported Mac savers work on both Intel and Apple Silicon machines.
Version 2.0 introduced an Apple Silicon native plugin along with a new screen saver engine, MovieSaver2.saver, which reduces CPU usage by 10x and cuts file size. New exports use this engine automatically, while existing installations and exports can be updated with the included UpgradeSavers.app. It's listed here as free.