Can you fully restore them right now officially with idevicerestore on all M1 Macs even if they are on either Windows or Linux? Is there any source for this?

Is that functionality in idevicerestore ready to use instead of using Apple Configurator?

I don't know about Windows, but it runs on Linux, yes, and it works on at least the M1 Mac Mini. See: https://github.com/libimobiledevice/idevicerestore/pull/406

There's some bug with the laptops, but it should be easy to fix once someone takes a good look at it. I might spend some time on that; I definitely want idevicerestore to be in good shape before we start encouraging more wide usage of Asahi. (https://github.com/libimobiledevice/idevicerestore/issues/41...)