If you’re planning on using plain Debian and the challenges that come with it, you probably should start with one of the pre-built images from the Debian foundation. You can mount the root partition with either a running linux box or WSL2. Then you can chroot into it to setup the wpa_supplicant.conf in the /etc/ folder and ensble sshd.
In case of Raspbian, you can create a wpa_supplicant.conf in the boot partition with:
network={
ssid="testing"
psk="testingPassword"
}
and a empty ssh file.
For the user config, since bullseye you need to make an account on first boot, that can be done with a userconf file, but it’s a bit more involved. You can see how to do it at the end of This blog post
Depends on the type of phone, usually it’s just finding out. You can also share it over Bluetooth within desktop mode, unsure about game mode.
Aside from what’s probably the problem which Moxvallix posted, maybe you could use a Hotspot from your phone with the VPN on to your steamdeck, it’ll allow you to access JF from your steamdeck for now I think.
on your profile settings on the web is a checkbox to mark it as a bot account.