SlideScroll

Tiling window managers split your screen into ever-smaller tiles. SlideScroll does the opposite: every window is a column on a strip that runs past the edges of the screen, at the width you chose. Open a window and it slides in beside the one you're using; nothing else changes size. Swipe with four fingers or press a shortcut to scroll the strip, the way niri and PaperWM work on Linux.

SlideScroll is free, open source, and a native Mac app, with no Electron, no web views and no account. Its only network access is checking GitHub for updates, which Settings can turn off.