Yes and they don't mention any language at all for Windows. Just "native", which is pretty much a philosophical question for that platform. I guess that means the founders have all avoided that platform their entire lives - which makes perfect sense but it means they have to trust their first engineering hire to make every consequential decision.
Personally I'd recommend they hire someone who has done native windows like its 2001 and is willing to use Zig.
Zig has bindings for Win32, etc., so a competent Windows developer should be as comfortable using that as C, C++, or whatever else people write Windows programs in these days. (At some point, it was intended that Windows programs would be written in Pascal, but that never caught on.)
Most of the time when I need to touch a Windows program I'm dealing with the Telegram desktop client which is C++ and a mixture of Qt and "native" Windows. (Well, that, and when I have to touch an ancient C# code base which requires doing the equivalent of archeology in order to get all of its dependent libraries to work.)
He says here that they have a direct Tailscale integration of the type that requires using the `tsnet` package, which is Go. Or at least would pull in the Go runtime as part of a shared library.
Interesting choice because tailscale is not free. Building in a paid third-party service is a questionable decision.
They better acquire it, if their product catches on.
Building with wireguard directly instead of tailscale would have been my choice, but of course it requires more plumbing.VC money means they gotta move fast.
But as a potential user, I won't pay for tailscale just to use their product.
There is nothing wrong with tailscale, it's just a dependency that can cost money charged by a third-party, so their product is less self-sovereign because it depends on tailscale keeping up a free tier.