Was there even a mention of a NW option? That would be where I’d go for this.
As to other sizes: I’m not sure that going down to a AAA-sized battery would work well, really. Runtime would be very short at anything above minimal brightness. But as a further novelty part of the ‘GT’ line, I almost expect it to be proposed. The midi format is already pretty competetively occupied, so it probably wouldn’t be as potentially lucrative as the much smaller sizes could be.