Would you mind sharing your hardware setup?

There is a way without Google Play outlined here: https://support.symfonium.app/t/how-can-i-pay-for-symfonium-without-google-play/1290/2

Try running which python before and after your source command. That should show where your Python executable is.

An old teacher of mine used to say “no news is good news” in Linux, so my guess is that your command is working but doesn’t show any output.

If you’re looking for a companion app, you might want to try KDE Connect. You can pair the mobile app to your Steam Deck to allow for keyboard/mouse remote input and a bunch of other cool features. There’s also a Decky plugin for KDE Connect in Gamescope.