I see you're having the problems with Guix that I was having.
To fix them, follow the instructions in [https://www.gnu.org/software/guix/manual/html_node/Application-Setup.html "Application Setup"] in the Guix manual. This should fix all the locale errors and stuff.
You also may have missed some search results because you didn't quote your query. Here's what happens when I don't quote it:
cal@leela:~$ guix package -s YouTube Qt guix package: error: Qt: extraneous argument But you're right, I didn't get anything when I searched it: cal@leela:~$ guix package -s 'YouTube Qt' cal@leela:~$
