I hade the same problem but i could solve it with some good old reading
https://www.raspberrypi.com/documentation/computers/os.html#python-on-raspberry-pi
I used the per-user enviroment
Use the following command to create a virtual environment in a hidden folder in the current user’s home directory:
python -m venv ~/.env
Run the following command from any directory to start using the virtual environment:
source ~/.env/bin/activate
You should then see a prompt similar to the following:
(.env) $:
To leave the virtual environment, run the following command from any directory:
deactivate
When you are inside your virtual environment you can install mmpm an can also use the whole commands like mmpm version ect.
Hope this helps