Many appliances run just fine on 120v DC power. Of course it's hard to tell which ones without either taking it apart and examining it or trying it and risking the magic smoke coming out.
Nothing high-current will ever switch to low voltage DC, I hope. I'm already annoyed at my 120v electric lawn mower; stupid extension cord is way heavier than my in-laws 240v electric lawn mower in Europe. Considering the cost of copper we should be switching to higher voltages, not lower.
Seems like the batteries could be redesigned to be higher voltage to reduce inverter losses. Just add more cells.
True sine wave IGBT converters are pretty efficient.
A sine curve goes off to infinity, or at least the end of the blackboard. -- Prof. Steiner