Honestly, just use Debian. It can run under 200MB of RAM (default install), so it beats all distros on the list except for TinyCore and SliTaz, and it actually has packages.

If the author really wants Blizzard to use his code then he doesn’t have much of a choice. Although since it has a GPL library the whole project is distributed under the GPL.

I believe OP has made some mistakes when pasting the text

[Diagram]
Oracle VM: Linux
External IP: 192.0.2.1
Internal IP: 172.16.0.2
 |
 | GRE Tunnel
 v
Home Server: Linux
Internal IP: 172.16.0.2
 |
 |
 v
Firewall: FreeBSD
Internal IP: 172.16.0.1
External IP: 192.0.2.2

[Text]
Home Linux Server GRE config:
$ sudo ip tunnel add gre0 mode gre remote 172.16.0.2 local 192.0.2.1 ttl 255
$ sudo ip link set gre0 up
$ sudo ip addr add 10.100.10.1/24 dev gre0


Home Linux Server GRE config:
$ sudo ip tunnel add gre0 mode gre remote 192.0.2.2 local 192.0.2.1 ttl 255
$ sudo ip link set gre0 up
$ sudo ip addr add 10.100.10.1/24 dev gre0

Firewall:
nat on igb1 inet from ! (igb1) to any -> (igb1:0)
nat on igb0 inet proto gre from 172.16.0.2 to any -> (igb1:0)
rdr pass on igb1 inet proto gre from 141.148.84.178 to (igb1) -> 172.16.0.2

Apart from being open source what is Linux?

The codebase in git.kernel.org’s torvalds/linux.git

Could I not create my own operating system that is different to windows or Macos and call it Steve

Of course, in fact many people have done so: TempleOS, MINIX, SerenityOS, etc.

What do you mean by «support»? In my Debian install I created an encrypted partition + LVM and I can hibernate without issue. I believe Ubuntu has an install option for encryption, so I think it should also work.

Flatpaks for graphical apps and guix for CLI programs and libraries.

The porterbox is a HiFie Unmatched.