It came as a surprise although I should have expected it: Pacifist can't open Install macOS Big Sur.app; the Catalina installer was the last one it could open.
(I assume it will continue to work with .dmg Deltas and Combos, but I couldn't test with the macOS 11.1 Delta because it doesn't appear on Apple's Downloads page. ¯\_(ツ)_/¯ )
According to
this article there will be no more standalone installers for Big Sur.
