I wonder if someone might indulge me by answering a question or two about Tailscale. I have a self-managed wireguard network which works, but probably isn't very smart or elegant.

From what I can gather, Tailscale does a lot of "magic" things to accomplish its goals, and some of them actually have "magic" right in the name. As a system administrator by trade, I have been bitten SO MANY TIMES by things that try to automagically mess with DNS resolution, routing tables, firewall rules, etc in the name of user-friendliness. (Often, things that even ship with the OS itself.)

Are there any documentation or articles detailing exactly what it's doing under the hood? I found https://tailscale.com/docs/concepts but it doesn't really cover everything.

If I have a virtualization host with, let's call it a "very custom" networking configuration, how likely is it to interfere with things? Is it polite and smart about working around fancy networking setups, or does it really only handle the common cases (one networking interface, a default route, public nameserver) elegantly?

I believe the client is open source and there's a reverse engineered server (that some tail scale employees contribute to)

Headscale is an open source alternative, I haven't read the code but it might be a good place to start: https://github.com/juanfont/headscale