Homebrew Python packages work by setting up their own package-specific virtual environments. This means you can upgrade them without waiting for the tap.
To find the virtual environment, run
head -n 1against the Homebrew-provided executable. For example, VisiData is
vd, so this works:
% head -n 1 $(which vd) #!/usr/local/Cellar/visidata/1.5.2/libexec/bin/python3.8
Now you can call
pipwithin that virtual directory to perform the upgrade like so:
/usr/local/Cellar/visidata/1.5.2/libexec/bin/pip install -U visidata