Steam Deck (or Linux) - Blocking a Game's Network Access
Is there a relatively simple way to block network access to a program? Avoiding the command line ideally.
Heroic Launcher has a "run game offline" toggle for games that are installed/added through it, but I am trying to cut out the middle man and install non-steam games directly through Steam.
You could also try installing ufw There's a guide here. There are also a bunch of GUI's made for ufw so you don't have to use the terminal to actually use the firewall. Apparently you will have to reinstall it everytime there is an update (for steam os presumably).
I haven't personally tried this stuff, but I think it might be easiest to make a bash script to run the commands to setup ufw so that you don't have to do it multiple times.
There is a built in firewall in steamos called iptables but its more for blocking access to ports system wide, and its also very painful to use.