Running the example from Matrix, everything works correctly.

Is the idea to allow to set netif->hostname later on, or it will stay global hostname setting?
And I guess, replacing SDK approach by removing wifi_station_... func from the SDK blobs, and using our own func setting netif->hostname?

Is the idea to allow to set netif->hostname later on, or it will stay global hostname setting?

Both are possible, I think keeping a common global name is better.
Like when you log in a computer with several network cards (ethernet, wifi) or a router: It's much easier when a single name designates a single place.

And I guess, replacing SDK approach by removing wifi_station_... func from the SDK blobs, and using our own func setting netif->hostname?

This is an interesting idea. For now I believe a sketch using the arduino API won't link these functions in.
We can open a new issue for core v4 about that.

Running the example from Matrix, everything works correctly.

Which matrix is it ?

Which matrix is it ?

Capital M one! Where you said it would be enough to check ./libraries/ESP8266WiFi/examples/IPv6/IPv6.ino example 🤷

This is an interesting idea. For now I believe a sketch using the arduino API won't link these functions in.
We can open a new issue for core v4 about that.

True, but it's the same issue as with dhcps funcs - NONOS SDK api stops working / interferes with the existing code. SDK part could also be --weaken-symbol=symbolname'd with the objcopy script, and we could have {get,set}hostname() doing this global setting. I will stop theorizing now as well, until the ethernet part works as intended on all fronts :)