Blender python interpreter

Blender's integrated Python interpreter lives in the Blender install folder:
../Blender Foundation/<version>/Python/bin

Any time you see a command that says python, you should instead use Blender's python interpreter.

so instead of

python -m pip install bqt

use

"C:\Program Files\Blender Foundation\Blender 3.2\3.2\python\bin\python.exe" -m pip install bqt

which is the same as

cd "C:\Program Files\Blender Foundation\Blender 3.2\3.2\python\bin"
python -m pip install bqt

(⚠️ note that Blender modifies it's paths on startup, so pip won't be aware of all installed modules)