If you have a computer with a BCM43142 wifi card like my Lenovo S20, you can get it working by using the broadcom-sta-dkms (https://packages.debian.org/buster/broadcom-sta-dkms) package from Debian's non-free repository.
02:00.0 Network controller: Broadcom Inc. and subsidiaries BCM43142 802.11b/g/n (rev 01)
