Yeah, that's what I've heard, and it's a decent solution, but I wouldn't run it with my actual seed phrase, and instead just test device matches website on a dummy one, in which case I don't have to worry about offline anyway, and I'd just be trusting the device behaves consistently from then on when I do my real seed phrase. I'd still however prefer to be able to do coin flips 11 at a time to pick words, since that's just more transparent to me, and I trust I can flip a coin without enough bias that it would matter (hence don't really care about the sha256 step with the dice rolls).