GNU/Linux Debian Buster Installing Broadcom BCM4312 Driver Guide
How to Install Broadcom BCM4312 Wi-fi/Bluetooth Driver on Debian Buster 10 GNU/Linux – Step by step Tutorial.
The Package Provides the Source Code for the wl Kernel Modules and makes use of the DKMS Build Utility to Install them for the Running Kernel.

GNU/Linux Debian 10 Broadcom BCM4312 Driver Installation Guide