when I install kicad 6.0.5 under windows, I get a pip.exe in the directory C:\Program Files\KiCad\6.0\bin\Scripts
If I then install kicad 6.0.6 over the previous install, pip.exe is deleted from the scripts directory.
And obviously pip does not work anymore in the kicad command prompt
If I keep a copy of the files pip.exe pip3.9.exe pip3.10.exe pip3.exe from the 6.0.5 installation. And then put them back in the Scripts directory after the 6.0.6 installation. Then pip seems to work fine, and my plugin also works.