The CUPS server should just work out of the box (not including printer setup) for Windows and Android as well. If the server you use is based on a recent-ish version from OpenPrinting (as it was on Debian 12, so about three years old), it should also work out of the box for iOS.
I’ve set this up although I can’t post the exact steps since it’s been so long ago. Here’s a summary.
Have a machine on the same network as the server. Setup dropbear-initramfs on your server to have a SSH server enabled on the luks unlock screen. You’ll have to set the SSH login command to unlock luks in authorized_keys. Then when you need to unlock your server from boot, use ssh with the -J option to jump to the server. Important here: use the local server ip address with respect to the secondary machine. e.g. ssh 192.168.1.1 -J secondary
In that example, 192.168.1.1 is your server address accessible from your secondary machine.
You can unlock remotely through this as well. I’ve setup Tailscale and can unlock my server when I need to reboot for kernel upgrades.
The original. I played the GameCube version. There was a separate menu in the game that let you setup the Internet connection in order to play online.
I do remember being able to access the web browser through some tricky steps when setting up the billing. There wasn’t an address bar anywhere on the UI by default but some combination of forward/back revealed it. Not all websites were supported on this stripped-down browser but it was fascinating.