Apple released macOS Big Sur 11.1 on 14 December. Although yesterday it finally posted standalone installers for the two concomitant security updates to Catalina and Mojave, no standalone updaters for Big Sur have appeared yet. Neither has it made available a standalone updater for macOS 11.0.1, which was released over a month ago.
If you feel that you “have a need for individual downloads for Big Sur delta/combo updaters”, please let Apple know. In the strongest possible terms, via Feedback, Apple Support and any other means available.
The lockdown continues.