Worked well with pip on a Pi 5 running Debian GNU/Linux 12 (Raspberry Pi O/S).
(Inside the weewx venv):
sudo systemctl stop weewx
pip install --upgrade pip <-- optional, but a good idea
python3 -m pip install weewx --upgrade
sudo systemctl start weewx
This took less than 5 minutes.
- Paul VE1DX