Don't worry, I made you a quick install script to setup Frida for your Specific use case:

#!/bin/sh

DIR="$HOME/Frida"
mkdir "$DIR"
cd "$DIR"

python -m venv "./python"
source "./python/bin/activate"

pip install frida-tools

wget https://github.com/frida/frida/releases/download/16.1.4/frida-server-16.1.4-linux-x86.xz
unxz frida-server-16.1.4-linux-x86.xz
chmod u+x frida-server-16.1.4-linux-x86

echo "#!/bin/sh
source ./python/bin/activate
frida -R -l _agent.js \$(pidof steam)" > inject.sh
chmod u+x inject.sh

echo "#!/bin/sh
sudo ./frida-server-16.1.4-linux-x86" > launch-server.sh

chmod u+x launch-server.sh

Make sure that your system has python3 installed, otherwise the script will most likely fail.

Now run my script, then download my _agent.js from https://anonymfile.com/84jO/agent.js and put it into your /home/YourUserName/Frida folder. After that navigate there and run ./launch-server.sh in your terminal. Open up another terminal in the same directory and enter ./inject.sh already, but don't press enter yet. Then startup steam and quickly execute the previously prepared ./inject.sh

That's it, good luck and enjoy :) If something's unclear feel free to reach out, and I know injecting it is annoying but I just can't be bothered to make yet another script to inject it fully automatically just yet