TunD. Make friends' PCs appear on the same VLAN

Hi HN! A few friends and I tried playing the video game Artemis (the fully cooperative Spaceship Bridge Simulator) together over LAN. For some reason, we couldn't all connect to the same network, so we decided to try using some free tool that would let us join the same virtual LAN without too much configuration (me and one other person were the only technical ones, and we had to explain it to other people who deliberately don't feel like learning technical stuff). The problem was that since we had different platforms (some on Windows, some on Mac, some on GNU/Linux), we couldn't find common ground, just wasted time. That's where the bet to try rewriting a virtual LAN generator that did more or less the same things came from (with the due/necessary limitations, but that would fulfill our main purpose), and that's how TunD was born:

https://danterolle.github.io/tund/

One machine runs as the hub, the others join as clients, and each gets a 10.9.0.x address. It uses UDP, supports basic IPv4 broadcast, and includes a CLI plus an optional Flutter desktop launcher.

I would love to get feedback both on using it and on the code itself. It is not perfect, but it works well for my use case, and maybe it will work well for others too.